To allocate a plurality of functions and programs as many as possible to one key like a single operation dial of a facsimile, and simply select a registered function in use.

The operation part of electronic equipment is equipped with a key top 35 supported so as to be capable of reciprocating inward and outward with a supporting hole 12 installed on the upper surface 2a of a casing cover and having a plurality of projecting contacts 36 on the lower surface; a printed circuit board 40 having a board side contact 41 being electrically connected to the projecting contact when the key top is pushed down; and a slot 11 for mounting a changing over plate, formed on the side surface of the casing cover, and communicating with the inside of the casing cover. When the changing over plate is completely inserted into the slot, the switching over plate is located in a space S between the lower surface of the key top and the printed circuit board, and each projecting contact of the key top is selectively electrically connected to each board side contact through the changing over plate.