Abstract: Disclosed is a clock spring-based rotational force generating device capable of allowing a user to freely adjust rotation speed of an output shaft and preventing the output shaft from rotating slowly or never rotating due to an weakened unwinding force of a spiral spring in the late period of an operation span of the spiral spring. The device includes an input shaft, a main drive gear receiving the rotational force of the input shaft, a spiral spring wound around a main drive gear shaft, a speed gear to increase the rotational force of the main drive gear, a power transmission control gear sliding up and down to control transmission of the rotational force of the main drive gear to the speed gear, an output shaft outputting the rotational force increased by the speed gear, and a rotation speed control means for controlling the rotation speed of the output shaft.