diff --git a/src/fiscal-periods/date-param.test.ts b/src/fiscal-periods/date-param.test.ts
index 127d613..2cd7f59 100644
--- a/src/fiscal-periods/date-param.test.ts
+++ b/src/fiscal-periods/date-param.test.ts
@@ -1,4 +1,5 @@
 import { DateParam } from '~/fiscal-periods/date-param'
+import { ParseError } from '~/fiscal-periods/error'
 
 test('toString', () => {
   expect(new DateParam('latest').toString()).toEqual('latest')
@@ -16,3 +17,14 @@ test('isLatest', () => {
   expect(new DateParam('latest').isLatest()).toBeTruthy()
   expect(new DateParam(new Date('2020-09-06')).isLatest()).toBeFalsy()
 })
+
+test('parse', () => {
+  expect(DateParam.parse('2020-09-06')).toEqual(
+    new DateParam(new Date(2020, 9, 6))
+  )
+  expect(DateParam.parse('latest')).toEqual(new DateParam('latest'))
+  expect(DateParam.parse('Latest')).toEqual(new DateParam('latest'))
+  expect(() => DateParam.parse('foo')).toThrow(ParseError)
+  expect(() => DateParam.parse('2020-9-6')).toThrow(ParseError)
+  expect(() => DateParam.parse('2020/09/06')).toThrow(ParseError)
+})
diff --git a/src/fiscal-periods/date-param.ts b/src/fiscal-periods/date-param.ts
index 55138c8..ac5f530 100644
--- a/src/fiscal-periods/date-param.ts
+++ b/src/fiscal-periods/date-param.ts
@@ -1,3 +1,5 @@
+import { ParseError } from '~/fiscal-periods/error'
+
 export class DateParam {
   constructor(public date: Date | 'latest') {}
 
@@ -20,4 +22,21 @@ export class DateParam {
   public isLatest(): boolean {
     return this.date === 'latest'
   }
+
+  static parse(str: string): DateParam {
+    str = str.toLowerCase()
+    if (str == 'latest') {
+      return new DateParam(str)
+    }
+
+    const matches = str.match(/^(\d{4})-(\d{2})-(\d{2})$/)
+    if (matches == undefined) {
+      throw new ParseError(`Invalid date format: ${str}`)
+    }
+
+    const year = parseInt(matches[1], 10)
+    const month = parseInt(matches[2], 10)
+    const day = parseInt(matches[3], 10)
+    return new DateParam(new Date(year, month, day))
+  }
 }
diff --git a/src/fiscal-periods/error.ts b/src/fiscal-periods/error.ts
index 61e93f3..0166913 100644
--- a/src/fiscal-periods/error.ts
+++ b/src/fiscal-periods/error.ts
@@ -24,3 +24,12 @@ export class InvalidLYLQError implements Error {
     this.message = message
   }
 }
+
+export class ParseError implements Error {
+  public name = 'ParseError'
+  public message: string
+
+  constructor(message = '') {
+    this.message = message
+  }
+}
diff --git a/src/fiscal-periods/period-parser.test.ts b/src/fiscal-periods/period-parser.test.ts
new file mode 100644
index 0000000..fbda466
--- /dev/null
+++ b/src/fiscal-periods/period-parser.test.ts
@@ -0,0 +1,17 @@
+import { DateParam } from '~/fiscal-periods/date-param'
+import { ParseError } from '~/fiscal-periods/error'
+import { PeriodParser } from '~/fiscal-periods/period-parser'
+import { YearQuarterParam } from '~/fiscal-periods/year-quarter-param'
+
+test('parse', () => {
+  expect(PeriodParser.parse('2020Q3')).toEqual(new YearQuarterParam(2020, 3))
+  expect(PeriodParser.parse('LYLQ')).toEqual(new YearQuarterParam('LY', 'LQ'))
+  expect(PeriodParser.parse('2020-09-06')).toEqual(
+    new DateParam(new Date(2020, 9, 6))
+  )
+  expect(() => PeriodParser.parse('foo')).toThrow(ParseError)
+  expect(() => PeriodParser.parse('2020LQ')).toThrow(ParseError)
+  expect(() => PeriodParser.parse('LYQ3')).toThrow(ParseError)
+  expect(() => PeriodParser.parse('2020/09/06')).toThrow(ParseError)
+  expect(() => PeriodParser.parse('latest')).toThrow(ParseError)
+})
diff --git a/src/fiscal-periods/period-parser.ts b/src/fiscal-periods/period-parser.ts
new file mode 100644
index 0000000..b1a9e7f
--- /dev/null
+++ b/src/fiscal-periods/period-parser.ts
@@ -0,0 +1,30 @@
+import { DateParam } from '~/fiscal-periods/date-param'
+import { ParseError } from '~/fiscal-periods/error'
+import { YearQuarterParam } from '~/fiscal-periods/year-quarter-param'
+
+export class PeriodParser {
+  constructor() {
+    // noop
+  }
+
+  static parse(str: string): DateParam | YearQuarterParam {
+    str = str.toUpperCase()
+
+    try {
+      return YearQuarterParam.parse(str)
+    } catch {
+      // noop
+    }
+
+    try {
+      const date = DateParam.parse(str)
+      if (!date.isLatest()) {
+        return date
+      }
+    } catch {
+      // noop
+    }
+
+    throw new ParseError(`Invalid period format: ${str}`)
+  }
+}
diff --git a/src/fiscal-periods/year-quarter-param.test.ts b/src/fiscal-periods/year-quarter-param.test.ts
index b44a25d..d6e5ea2 100644
--- a/src/fiscal-periods/year-quarter-param.test.ts
+++ b/src/fiscal-periods/year-quarter-param.test.ts
@@ -1,7 +1,8 @@
 import {
   InvalidLYLQError,
   InvalidYearError,
-  InvalidQuarterError
+  InvalidQuarterError,
+  ParseError
 } from '~/fiscal-periods/error'
 import { YearQuarter } from '~/fiscal-periods/year-quarter'
 import { YearQuarterParam } from '~/fiscal-periods/year-quarter-param'
@@ -50,3 +51,22 @@ test('fromYearQuarter', () => {
     new YearQuarterParam(2018, 1)
   )
 })
+
+test('parse', () => {
+  expect(YearQuarterParam.parse('2020Q3')).toEqual(
+    new YearQuarterParam(2020, 3)
+  )
+  expect(YearQuarterParam.parse('2020q3')).toEqual(
+    new YearQuarterParam(2020, 3)
+  )
+  expect(YearQuarterParam.parse('LYLQ')).toEqual(
+    new YearQuarterParam('LY', 'LQ')
+  )
+  expect(YearQuarterParam.parse('lylq')).toEqual(
+    new YearQuarterParam('LY', 'LQ')
+  )
+  expect(() => YearQuarterParam.parse('20Q3')).toThrow(ParseError)
+  expect(() => YearQuarterParam.parse('LYQ3')).toThrow(InvalidLYLQError)
+  expect(() => YearQuarterParam.parse('2020LQ')).toThrow(InvalidLYLQError)
+  expect(() => YearQuarterParam.parse('foo')).toThrow(ParseError)
+})
diff --git a/src/fiscal-periods/year-quarter-param.ts b/src/fiscal-periods/year-quarter-param.ts
index ceba3d1..d319380 100644
--- a/src/fiscal-periods/year-quarter-param.ts
+++ b/src/fiscal-periods/year-quarter-param.ts
@@ -1,7 +1,8 @@
 import {
   InvalidLYLQError,
   InvalidYearError,
-  InvalidQuarterError
+  InvalidQuarterError,
+  ParseError
 } from '~/fiscal-periods/error'
 import { YearQuarter } from '~/fiscal-periods/year-quarter'
 
@@ -44,6 +45,20 @@ export class YearQuarterParam {
     return this.quarter === 'LQ'
   }
 
+  // XXX: LYLQの同時指定や-1などの相対値指定をどうするか確認する
+  static parse(str: string): YearQuarterParam {
+    str = str.toUpperCase()
+    const matches = str.match(/^(\d{4}|LY)(Q\d|LQ)$/)
+    if (matches == undefined) {
+      throw new ParseError(`Invalid year-quarter format: ${str}`)
+    }
+
+    const year = matches[1] === 'LY' ? 'LY' : parseInt(matches[1], 10)
+    const quarter =
+      matches[2] === 'LQ' ? 'LQ' : parseInt(matches[2].substring(1), 10)
+    return new YearQuarterParam(year, quarter)
+  }
+
   static fromYearQuarter(period: YearQuarter): YearQuarterParam {
     return new YearQuarterParam(period.year, period.quarter)
   }