To provide a speed control device capable of regulating the speed with a simplified mechanism in a toy powered by energizing force of a spring.

An O ring 16 comprising a rubber compound is installed in a passage 15 defined by a movable shaft 14, driven by the energizing force of a spiral spring 3 as a source of power, and a casing 11. The O ring 16 is configured to move in a direction of rotation of the movable shaft 14 inside the passage 15 by the slide contact force produced with the movable shaft 14 when the movable shaft 14 is rotated, and the rotating speed of the movable shaft 14 is made to be decelerated by frictional resistance received from the O ring 16.