diff --git a/arai60/21-29_Tree_BT_BST/22_111_Minimum Depth of Binary Tree/level_1.py b/arai60/21-29_Tree_BT_BST/22_111_Minimum Depth of Binary Tree/level_1.py
new file mode 100644
index 0000000..0aeb833
--- /dev/null
+++ b/arai60/21-29_Tree_BT_BST/22_111_Minimum Depth of Binary Tree/level_1.py	
@@ -0,0 +1,57 @@
+# BFS
+class Solution:
+    def minDepth(self, root: Optional[TreeNode]) -> int:
+        if not root:
+            return 0
+        node_queue = deque([(root, 0)])
+        while node_queue:
+            node, depth = node_queue.popleft()
+            if not node.left and not node.right:
+                break
+            if node.left:
+                node_queue.append((node.left, depth + 1))
+            if node.right:
+                node_queue.append((node.right, depth + 1))
+        min_node_num = depth + 1
+        return min_node_num
+
+
+# DFS
+class Solution:
+    def minDepth(self, root: Optional[TreeNode]) -> int:
+        def search_min_depth(node):
+            if not node.left and not node.right:
+                return 0
+            left_depth = float(inf)
+            right_depth = float(inf)
+            if node.left:
+                left_depth = search_min_depth(node.left) + 1
+            if node.right:
+                right_depth = search_min_depth(node.right) + 1
+            min_depth = min(left_depth, right_depth)
+            return min_depth
+
+        if not root:
+            return 0
+        min_node_num = search_min_depth(root) + 1
+        return min_node_num
+
+
+# DFSをstackで実装
+class Solution:
+    def minDepth(self, root: Optional[TreeNode]) -> int:
+        if not root:
+            return 0
+        node_depth_stack = [(root, 0)]
+        min_depth = float(inf)
+        while node_depth_stack:
+            node, depth = node_depth_stack.pop()
+            if not node.left and not node.right:
+                min_depth = min(min_depth, depth)
+                continue
+            if node.right:
+                node_depth_stack.append((node.right, depth + 1))
+            if node.left:
+                node_depth_stack.append((node.left, depth + 1))
+        min_node_num = min_depth + 1
+        return min_node_num
diff --git a/arai60/21-29_Tree_BT_BST/22_111_Minimum Depth of Binary Tree/level_2.py b/arai60/21-29_Tree_BT_BST/22_111_Minimum Depth of Binary Tree/level_2.py
new file mode 100644
index 0000000..ec436c8
--- /dev/null
+++ b/arai60/21-29_Tree_BT_BST/22_111_Minimum Depth of Binary Tree/level_2.py	
@@ -0,0 +1,51 @@
+# BFS
+class Solution:
+    def minDepth(self, root: Optional[TreeNode]) -> int:
+        if not root:
+            return 0
+        node_depth_queue = deque([(root, 0)])
+        while node_depth_queue:
+            node, depth = node_depth_queue.popleft()
+            if not node.left and not node.right:
+                return depth + 1
+            if node.left:
+                node_depth_queue.append((node.left, depth + 1))
+            if node.right:
+                node_depth_queue.append((node.right, depth + 1))
+
+
+# DFS
+# left_depthとright_depthをmin_depthに統合
+# min_depthの初期値をintの最大値に変更
+class Solution:
+    def minDepth(self, root: Optional[TreeNode]) -> int:
+        if not root:
+            return 0
+        if not root.left and not root.right:
+            return 1
+        min_depth = sys.maxsize
+        if root.left:
+            min_depth = min(min_depth, self.minDepth(root.left) + 1)
+        if root.right:
+            min_depth = min(min_depth, self.minDepth(root.right) + 1)
+        return min_depth
+
+
+# DFSをstackで実装
+# min_depthの初期値をintの最大値に変更
+class Solution:
+    def minDepth(self, root: Optional[TreeNode]) -> int:
+        if not root:
+            return 0
+        node_depth_stack = [(root, 0)]
+        min_depth = sys.maxsize
+        while node_depth_stack:
+            node, depth = node_depth_stack.pop()
+            if not node.left and not node.right:
+                min_depth = min(min_depth, depth)
+                continue
+            if node.right:
+                node_depth_stack.append((node.right, depth + 1))
+            if node.left:
+                node_depth_stack.append((node.left, depth + 1))
+        return min_depth + 1
diff --git a/arai60/21-29_Tree_BT_BST/22_111_Minimum Depth of Binary Tree/level_3.py b/arai60/21-29_Tree_BT_BST/22_111_Minimum Depth of Binary Tree/level_3.py
new file mode 100644
index 0000000..1edddb1
--- /dev/null
+++ b/arai60/21-29_Tree_BT_BST/22_111_Minimum Depth of Binary Tree/level_3.py	
@@ -0,0 +1,16 @@
+
+class Solution:
+    def minDepth(self, root: Optional[TreeNode]) -> int:
+        if not root:
+            return 0
+        node_depth_queue = deque([(root, 0)])
+        while node_depth_queue:
+            node, depth = node_depth_queue.popleft()
+            if not node.left and not node.right:
+                break
+            if node.left:
+                node_depth_queue.append((node.left, depth + 1))
+            if node.right:
+                node_depth_queue.append((node.right, depth + 1))
+        min_node_num = depth + 1
+        return min_node_num