PURPOSE: To realize a smooth on/off operation without the occurrence of the operation failure such as twist with simple structure by integrally molding a button member and a spring member.

CONSTITUTION: An eject button 29 consists of the button member 80 and the spring member 81 which is continuously and integrally molded on one side of the member 80. The spring member 81 is bent at right angles in the lateral direction cross to the longitudinal direction of the button memory 80. The rigidity of the connection part of the button member 80 and the spring member 81 is set lower than the other parts by narrowing the width. In case of attaching the button 29, the spring member 81 can easily and elastically be deformed thereby improving assembling quality. A shaft-like stopper part 86 whose diameter is larger than the plate thickness of the spring member 81 is formed at the end part of the spring member 81 opposite to the button member 80. Polypropylene(PP) and polyethylene(PE), for example, are suitable for the material quality of the eject button 29, and various plastics can be used also therefor.