A PDA as an apparatus actuated by key operations comprises: a substrate; an exothermic semiconductor device provided on a first major surface of the substrate; a plurality of switches provided on a second major surface of the substrate; a key mat located on the side of the second major surface of the substrate; a plurality of pressure conveying portions protruding from one of the major surfaces of the key mat toward each of the plurality of switches, the one of the major surfaces facing the second major surface of the substrate; and a key that is provided on the other major surface of the key mat and that can be pressed down to the key mat. A contact face between the particular switch located within a certain range of the distance from the semiconductor device, and the pressure conveying portion corresponding to the particular switch, has a smaller area as compared to that of a contact face between the non-particular switch, which is a switch other than the particular switch, and the pressure conveying portion corresponding to the non-particular switch.