diff --git a/index.d.test.ts b/index.d.test.ts
new file mode 100644
index 000000000..71a2ae5a9
--- /dev/null
+++ b/index.d.test.ts
@@ -0,0 +1,71 @@
+import dayjs from '.'
+
+dayjs()
+
+dayjs('1993-03-1')
+
+dayjs(730944000000)
+
+dayjs(new Date(1993, 3, 1))
+
+dayjs().clone()
+
+dayjs().isValid()
+
+dayjs().year()
+
+dayjs().month()
+
+dayjs().date()
+
+dayjs().hour()
+
+dayjs().minute()
+
+dayjs().second()
+
+dayjs().millisecond()
+
+dayjs().set('month', 3)
+dayjs().set('second', 30)
+
+dayjs().add(7, 'day')
+
+dayjs().subtract(7, 'year')
+
+dayjs().startOf('year')
+
+dayjs().endOf('month')
+
+dayjs().startOf('month').add(1, 'day').subtract(1, 'year')
+
+dayjs().format()
+dayjs().format('[YYYY] MM-DDTHH:mm:ssZ')
+
+dayjs().diff(dayjs(), 'year')
+
+dayjs().valueOf()
+
+dayjs().unix()
+
+dayjs().daysInMonth()
+
+dayjs().toDate()
+
+dayjs().toArray()
+
+dayjs().toJSON()
+
+dayjs().toISOString()
+
+dayjs().toObject()
+
+dayjs().toString()
+
+dayjs().isBefore(dayjs())
+
+dayjs().isSame(dayjs())
+
+dayjs().isAfter(dayjs())
+
+dayjs('2000-01-01').isLeapYear(dayjs())
diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 000000000..d70fac9fd
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,83 @@
+// Type definitions for dayjs 1.0
+// Project: https://github.com/xx45/dayjs
+// Definitions by: varHarrie <https://github.com/varHarrie>
+
+type ConfigType = string | number | Date | Dayjs
+
+type UnitType = 'millisecond' | 'second' | 'minute' | 'hour' | 'day' | 'week' | 'month' | 'quarter' | 'year' | 'date'
+
+interface DayjsObject {
+  years: number
+  months: number
+  date: number
+  hours: number
+  minutes: number
+  seconds: number
+  milliseconds: number
+}
+
+declare class Dayjs {
+  constructor (config?: ConfigType)
+
+  clone(): Dayjs
+
+  isValid(): boolean
+
+  year(): number
+
+  month(): number
+
+  date(): number
+
+  hour(): number
+
+  minute(): number
+
+  second(): number
+
+  millisecond(): number
+
+  set(unit: UnitType, value: number): Dayjs
+
+  add(value: number, unit: UnitType): Dayjs
+
+  subtract(value: number, unit: UnitType): Dayjs
+
+  startOf(unit: UnitType): Dayjs
+
+  endOf(unit: UnitType): Dayjs
+
+  format(template?: string): string
+
+  diff(dayjs: Dayjs, unit: UnitType, float?: boolean): number
+
+  valueOf(): number
+
+  unix(): number
+
+  daysInMonth(): number
+
+  toDate(): Date
+
+  toArray(): number[]
+
+  toJSON(): string
+
+  toISOString(): string
+
+  toObject(): Object
+
+  toString(): string
+
+  isBefore(dayjs: Dayjs): boolean
+
+  isSame(dayjs: Dayjs)
+
+  isAfter(dayjs: Dayjs)
+
+  isLeapYear(dayjs?: Dayjs): boolean
+}
+
+declare function dayjs (config?: ConfigType): Dayjs
+
+export default dayjs
diff --git a/package.json b/package.json
index 37830afc7..64d036f4d 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,7 @@
   "version": "0.0.0-development",
   "description": "",
   "main": "dist/dayjs.min.js",
+  "types": "index.d.ts",
   "scripts": {
     "test": "jest",
     "lint": "./node_modules/.bin/eslint src/* test/*",