PURPOSE: To eliminate generation of vibration and a noise by moving a push- button type operation member from an initial position when an operation part is pressed, pressing a part to be pressed of a switch by a pressing part, and returning it to the initial position against returning force when pressing force to the operation part is released.

CONSTITUTION: A push-button type operation member 40 is integrally molded by a material having a certain degree of elasticity, for example, like synthetic resin, and is normally pressed in the clockwise direction shown by an arrow A with a fulcrum part 40d as the center by returning force generated by a returning force generating part 40b. In this condition, the extending end of a pressing part 40c upward separates from a part DM to be pressed of a push- button type switch SW of a circuit board 33. Since an operation part 40a is pressed to an inside end peripheral part of an opening 32 on an inner peripheral surface of the opening part 32 of a switch operating part of an enclosing body or an inside surface of a side wall of the enclosing body by returning force generated by this generating part 40b, the member 40 does not generate vibration by microvibration applied to the enclosing body, so that a noise is not generated too thereby.