PURPOSE: To input a required signal to an external device from an object device not having any output terminal by delivering an external mechanical force to a switch of the object device and also converting operating information of the switch into a non-mechanical output signal.

CONSTITUTION: In depressing a pushbutton 18 exposed at the outside of a decoration board 16, a push rod 8 is lowered and a button switch 4 of a telephone set 2 is operated. On the other hand, when the push rod 8 is lowered, one end of a spring sheet 24 is lowered, one end contacts a conductor 22, which is made conductive. Thus, a signal flowing into the conductor 22 reaches an external computer 10 from a terminal provided to the conductor 22 via other interface. In stopping the depression of the pushbutton switch 18, the push rod 8 and the pushbutton 18 are restored to the home position by the elasticity of a spring sheet 24, the conductor 22 is made nonconductive and no current flows to the external computer 10.