To provide a winding device capable of being miniaturized and lightened while securing a sufficient strength of not being broken by a tensile force acting on a long material.

The winding device 16 includes a rotary body 56 having a winding part 70 for winding a lead string 14 (the long material), a lead string-storing case 18 (a base part) for freely rotatably supporting the rotary body 56, a spiral spring 48, a locking part 38 and a lock-releasing part 32. The winding part 70 has a spiral spring-storing part 76, and the locking part 38 is integrally formed with the terminal face of the rotary body 56 in the shaft direction, and has a plurality of first engaging parts 88 arranged on the periphery of the rotary shaft P at an interval in the perimeter direction, and a plurality of second engaging parts 40 integrally formed with the lead string-storing case 18, and simultaneously engaging with the plurality of the first engaging parts 88 from the perimeter direction. The lock-releasing part 32 has a movable mechanism F for releasing the engaged state by parallelly moving the rotary body 56 based on the rotary shaft P.