diff --git a/src/App.test.jsx b/src/App.test.jsx
index b6fe691..3d85f28 100644
--- a/src/App.test.jsx
+++ b/src/App.test.jsx
@@ -30,6 +30,10 @@ describe('App', () => {
         writeField: {
           tags: [],
         },
+        applyFields: {
+          reason: '',
+          wantToGet: '',
+        },
       },
       authReducer: {
         register: {
diff --git a/src/components/introduce/IntroduceHeader.jsx b/src/components/introduce/IntroduceHeader.jsx
index 29328a2..a48a2ba 100644
--- a/src/components/introduce/IntroduceHeader.jsx
+++ b/src/components/introduce/IntroduceHeader.jsx
@@ -24,7 +24,7 @@ const IntroduceHeaderWrapper = styled.div`
 `;
 
 const IntroduceHeader = ({
-  group, onApply, user, realTime, onApplyCancel,
+  group, onApply, user, realTime, onApplyCancel, onChangeApplyFields, applyFields,
 }) => {
   const [loginCheckModal, setLoginCheckModal] = useState(false);
   const [applyCancelModal, setApplyCancelModal] = useState(false);
@@ -96,6 +96,8 @@ const IntroduceHeader = ({
             visible={modalForm}
             onCancel={handleFormCancel}
             onConfirm={handleFormSubmit}
+            onChangeApply={onChangeApplyFields}
+            fields={applyFields}
           />
         </>
       )}
diff --git a/src/components/introduce/IntroduceHeader.test.jsx b/src/components/introduce/IntroduceHeader.test.jsx
index a3ba9aa..c905cc1 100644
--- a/src/components/introduce/IntroduceHeader.test.jsx
+++ b/src/components/introduce/IntroduceHeader.test.jsx
@@ -18,6 +18,7 @@ describe('IntroduceHeader', () => {
     <IntroduceHeader
       user={user}
       group={group}
+      applyFields={{ reason: '', wantToGet: '' }}
       realTime={time}
       onApply={handleApply}
       onApplyCancel={handleApplyCancel}
@@ -203,21 +204,39 @@ describe('IntroduceHeader', () => {
         personnel: 2,
       };
 
-      it('renders modal window appears and application failure message', () => {
-        const { container, getByText } = renderIntroduceHeader({ group, time, user: 'user' });
+      context('Click confirm Study participation application', () => {
+        it('renders modal window appears and application failure message', () => {
+          const { container, getByText } = renderIntroduceHeader({ group, time, user: 'user' });
 
-        const button = getByText('신청하기');
+          const button = getByText('신청하기');
 
-        expect(button).not.toBeNull();
+          expect(button).not.toBeNull();
 
-        fireEvent.click(button);
+          fireEvent.click(button);
 
-        // TODO: 이 부분은 추후 변경해야된다 현재 스터디 참여 신청서 모달창이 나타남.
-        fireEvent.click(getByText('확인'));
+          // TODO: 이 부분은 추후 변경해야된다 현재 스터디 참여 신청서 모달창이 나타남.
+          fireEvent.click(getByText('확인'));
 
-        expect(handleApply).toBeCalled();
+          expect(handleApply).toBeCalled();
 
-        expect(container).not.toHaveTextContent('로그인 후 신청 가능합니다.');
+          expect(container).not.toHaveTextContent('로그인 후 신청 가능합니다.');
+        });
+      });
+
+      context('Click cancel Study participation application', () => {
+        it('renders modal window appears and application failure message', () => {
+          const { getByText } = renderIntroduceHeader({ group, time, user: 'user' });
+
+          const button = getByText('신청하기');
+
+          expect(button).not.toBeNull();
+
+          fireEvent.click(button);
+
+          fireEvent.click(getByText('취소'));
+
+          expect(handleApply).not.toBeCalled();
+        });
       });
     });
   });
diff --git a/src/components/introduce/modals/ApplicationFormModal.jsx b/src/components/introduce/modals/ApplicationFormModal.jsx
index 4f65519..37c6947 100644
--- a/src/components/introduce/modals/ApplicationFormModal.jsx
+++ b/src/components/introduce/modals/ApplicationFormModal.jsx
@@ -40,7 +40,7 @@ const ApplicationFormModalWrapper = styled.div`
 const ModalBoxWrapper = styled.div`
   display: flex;
   flex-direction: column;
-  height: 570px;
+  height: 575px;
   width: 400px;
   background: white;
   padding: 1.5rem;
@@ -84,13 +84,17 @@ const ContentTextareaWrapper = styled.textarea`
   padding: 5px;
   resize: none;
   outline: none;
-  border: 1px solid ${palette.gray[3]};
+  border: 2px solid #D7E2EB;
   border-radius: 3px;
   font-weight: bold;
   color: rgb(33, 37, 41);
   margin-bottom: 0.7rem;
-  &:hover, &:focus {
-    border: 2px solid ${palette.gray[4]};
+  transition-duration: 0.08s;
+  transition-property: all;
+  transition-timing-function: ease-in-out;
+  transition-delay: initial;
+  &:focus {
+    border: 2px solid ${palette.teal[5]};
   }
 `;
 
@@ -100,7 +104,17 @@ const StyledButton = styled(Button)`
   }
 `;
 
-const ApplicationFormModal = ({ visible, onCancel, onConfirm }) => {
+const ApplicationFormModal = ({
+  visible, onCancel, onConfirm, onChangeApply, fields,
+}) => {
+  const { reason, wantToGet } = fields;
+
+  const handleChange = (e) => {
+    const { name, value } = e.target;
+
+    onChangeApply({ name, value });
+  };
+
   if (!visible) {
     return null;
   }
@@ -111,11 +125,25 @@ const ApplicationFormModal = ({ visible, onCancel, onConfirm }) => {
         <h2>스터디 참여 신청서 📚</h2>
         <ContentBoxWrapper>
           <label htmlFor="apply-reason">신청하게 된 이유</label>
-          <ContentTextareaWrapper placeholder="내용을 입력해주세요." id="apply-reason" rows="10" />
+          <ContentTextareaWrapper
+            rows="10"
+            id="apply-reason"
+            name="reason"
+            placeholder="내용을 입력해주세요."
+            value={reason}
+            onChange={handleChange}
+          />
         </ContentBoxWrapper>
         <ContentBoxWrapper>
-          <label htmlFor="apply-reason">스터디를 통해 얻고 싶은 것은 무엇인가요?</label>
-          <ContentTextareaWrapper placeholder="내용을 입력해주세요." id="study-want" rows="10" />
+          <label htmlFor="study-want">스터디를 통해 얻고 싶은 것은 무엇인가요?</label>
+          <ContentTextareaWrapper
+            rows="10"
+            id="study-want"
+            name="wantToGet"
+            placeholder="내용을 입력해주세요."
+            value={wantToGet}
+            onChange={handleChange}
+          />
         </ContentBoxWrapper>
         <div className="buttons">
           <StyledButton onClick={onCancel}>취소</StyledButton>
diff --git a/src/components/introduce/modals/ApplicationFormModal.test.jsx b/src/components/introduce/modals/ApplicationFormModal.test.jsx
index cdb1f00..bb9479a 100644
--- a/src/components/introduce/modals/ApplicationFormModal.test.jsx
+++ b/src/components/introduce/modals/ApplicationFormModal.test.jsx
@@ -7,10 +7,13 @@ import ApplicationFormModal from './ApplicationFormModal';
 describe('ApplicationFormModal', () => {
   const handleCancel = jest.fn();
   const handleConfirm = jest.fn();
+  const handleChange = jest.fn();
 
-  const renderApplicationFormModal = ({ visible }) => render((
+  const renderApplicationFormModal = ({ visible, fields }) => render((
     <ApplicationFormModal
       visible={visible}
+      fields={fields}
+      onChangeApply={handleChange}
       onConfirm={handleConfirm}
       onCancel={handleCancel}
     />
@@ -19,6 +22,10 @@ describe('ApplicationFormModal', () => {
   context('with visible', () => {
     const modal = {
       visible: true,
+      fields: {
+        reason: '',
+        wantToGet: '',
+      },
     };
 
     it('renders Modal text', () => {
@@ -48,11 +55,25 @@ describe('ApplicationFormModal', () => {
 
       expect(handleCancel).toBeCalled();
     });
+
+    it('change apply form fields', () => {
+      const { getByLabelText } = renderApplicationFormModal(modal);
+
+      const input = getByLabelText('신청하게 된 이유');
+
+      fireEvent.change(input, { target: { name: 'reason', value: '내용' } });
+
+      expect(handleChange).toBeCalled();
+    });
   });
 
   context('without visible', () => {
     const modal = {
       visible: false,
+      fields: {
+        reason: '',
+        wantToGet: '',
+      },
     };
 
     it("doesn't renders Modal text", () => {
diff --git a/src/containers/introduce/IntroduceContainer.jsx b/src/containers/introduce/IntroduceContainer.jsx
index 1a8b470..bf636fb 100644
--- a/src/containers/introduce/IntroduceContainer.jsx
+++ b/src/containers/introduce/IntroduceContainer.jsx
@@ -4,7 +4,9 @@ import { useInterval } from 'react-use';
 import { useDispatch, useSelector } from 'react-redux';
 
 import { getAuth, getGroup } from '../../util/utils';
-import { deleteParticipant, loadStudyGroup, updateParticipant } from '../../reducers/groupSlice';
+import {
+  changeApplyFields, deleteParticipant, loadStudyGroup, updateParticipant,
+} from '../../reducers/groupSlice';
 
 import StudyIntroduceForm from '../../components/introduce/StudyIntroduceForm';
 import GroupContentLoader from '../../components/introduce/GroupsContentLoader';
@@ -15,6 +17,7 @@ const IntroduceContainer = ({ groupId }) => {
 
   const dispatch = useDispatch();
 
+  const applyFields = useSelector(getGroup('applyFields'));
   const group = useSelector(getGroup('group'));
   const user = useSelector(getAuth('user'));
 
@@ -34,6 +37,10 @@ const IntroduceContainer = ({ groupId }) => {
     dispatch(deleteParticipant());
   }, [dispatch]);
 
+  const onChangeApplyFields = useCallback(({ name, value }) => {
+    dispatch(changeApplyFields({ name, value }));
+  }, [dispatch]);
+
   if (!group) {
     return (
       <GroupContentLoader />
@@ -46,8 +53,10 @@ const IntroduceContainer = ({ groupId }) => {
         user={user}
         group={group}
         realTime={realTime}
+        applyFields={applyFields}
         onApply={onApplyStudy}
         onApplyCancel={onApplyCancel}
+        onChangeApplyFields={onChangeApplyFields}
       />
       <StudyIntroduceForm
         group={group}
diff --git a/src/containers/introduce/IntroduceContainer.test.jsx b/src/containers/introduce/IntroduceContainer.test.jsx
index 57e41f3..2d058cd 100644
--- a/src/containers/introduce/IntroduceContainer.test.jsx
+++ b/src/containers/introduce/IntroduceContainer.test.jsx
@@ -24,6 +24,7 @@ describe('IntroduceContainer', () => {
       },
       groupReducer: {
         group: given.group,
+        applyFields: given.applyFields,
       },
     }));
   });
@@ -48,6 +49,10 @@ describe('IntroduceContainer', () => {
         'Algorithm',
       ],
     }));
+    given('applyFields', () => ({
+      reason: '',
+      wantToGet: '',
+    }));
 
     it('renders study group title and contents', () => {
       const { container } = renderIntroduceContainer(1);
@@ -65,6 +70,10 @@ describe('IntroduceContainer', () => {
 
   context('without group ', () => {
     given('group', () => (null));
+    given('applyFields', () => ({
+      reason: '',
+      wantToGet: '',
+    }));
 
     it('renders "loading.." text', () => {
       const { container } = renderIntroduceContainer(1);
@@ -76,6 +85,10 @@ describe('IntroduceContainer', () => {
   context('with group & user', () => {
     given('group', () => (STUDY_GROUP));
     given('user', () => ('user'));
+    given('applyFields', () => ({
+      reason: '',
+      wantToGet: '',
+    }));
 
     it('click event dispatches action call updateParticipant', () => {
       const { getByText } = renderIntroduceContainer(1);
@@ -93,6 +106,30 @@ describe('IntroduceContainer', () => {
 
       expect(dispatch).toBeCalledTimes(2);
     });
+
+    it('dispatches action calls changeApplyFields', () => {
+      const form = {
+        name: 'reason',
+        value: '내용',
+      };
+
+      const { getByText, getByLabelText } = renderIntroduceContainer(1);
+
+      expect(dispatch).toBeCalledTimes(1);
+
+      const button = getByText('신청하기');
+
+      fireEvent.click(button);
+
+      const input = getByLabelText('신청하게 된 이유');
+
+      fireEvent.change(input, { target: form });
+
+      expect(dispatch).toBeCalledWith({
+        type: 'group/changeApplyFields',
+        payload: form,
+      });
+    });
   });
 
   describe(`When the application date is earlier than the deadline 
@@ -112,6 +149,10 @@ describe('IntroduceContainer', () => {
 
     given('group', () => (group));
     given('user', () => ('user'));
+    given('applyFields', () => ({
+      reason: '',
+      wantToGet: '',
+    }));
 
     context('click confirm', () => {
       it('click event dispatches action call deleteParticipant', () => {
diff --git a/src/pages/IntroducePage.test.jsx b/src/pages/IntroducePage.test.jsx
index b4d3666..78e8684 100644
--- a/src/pages/IntroducePage.test.jsx
+++ b/src/pages/IntroducePage.test.jsx
@@ -28,6 +28,10 @@ describe('IntroducePage', () => {
             'Algorithm',
           ],
         },
+        applyFields: {
+          reason: '',
+          wantToGet: '',
+        },
       },
       authReducer: {},
     }));
diff --git a/src/reducers/groupSlice.js b/src/reducers/groupSlice.js
index 7f8b84f..1ce9978 100644
--- a/src/reducers/groupSlice.js
+++ b/src/reducers/groupSlice.js
@@ -20,6 +20,11 @@ const writeInitialState = {
   tags: [],
 };
 
+const applyInitialState = {
+  reason: '',
+  wantToGet: '',
+};
+
 const { actions, reducer } = createSlice({
   name: 'group',
   initialState: {
@@ -27,6 +32,7 @@ const { actions, reducer } = createSlice({
     group: null,
     groupId: null,
     writeField: writeInitialState,
+    applyFields: applyInitialState,
   },
 
   reducers: {
@@ -45,15 +51,9 @@ const { actions, reducer } = createSlice({
     },
 
     changeWriteField(state, { payload: { name, value } }) {
-      const { writeField } = state;
-
-      return {
-        ...state,
-        writeField: {
-          ...writeField,
-          [name]: value,
-        },
-      };
+      return produce(state, (draft) => {
+        draft.writeField[name] = value;
+      });
     },
 
     clearWriteFields(state) {
@@ -70,6 +70,12 @@ const { actions, reducer } = createSlice({
         groupId,
       };
     },
+
+    changeApplyFields(state, { payload: { name, value } }) {
+      return produce(state, (draft) => {
+        draft.applyFields[name] = value;
+      });
+    },
   },
 });
 
@@ -79,6 +85,7 @@ export const {
   changeWriteField,
   clearWriteFields,
   successWrite,
+  changeApplyFields,
 } = actions;
 
 export const loadStudyGroups = (tag) => async (dispatch) => {
diff --git a/src/reducers/groupSlice.test.js b/src/reducers/groupSlice.test.js
index aa92267..b944649 100644
--- a/src/reducers/groupSlice.test.js
+++ b/src/reducers/groupSlice.test.js
@@ -14,6 +14,7 @@ import reducer, {
   successWrite,
   updateParticipant,
   deleteParticipant,
+  changeApplyFields,
 } from './groupSlice';
 
 import STUDY_GROUPS from '../../fixtures/study-groups';
@@ -40,6 +41,10 @@ describe('reducer', () => {
         personnel: '1',
         tags: [],
       },
+      applyFields: {
+        reason: '',
+        wantToGet: '',
+      },
     };
 
     it('returns initialState', () => {
@@ -128,6 +133,24 @@ describe('reducer', () => {
       expect(state.groupId).toBe('1');
     });
   });
+
+  describe('changeApplyFields', () => {
+    it('changes a field of study participation application form', () => {
+      const initialState = {
+        applyFields: {
+          reason: '',
+          wantToGet: '',
+        },
+      };
+
+      const state = reducer(
+        initialState,
+        changeApplyFields({ name: 'reason', value: '참여합니다.' }),
+      );
+
+      expect(state.applyFields.reason).toBe('참여합니다.');
+    });
+  });
 });
 
 describe('async actions', () => {