A key switch structure is provided with a key switch located in a position corresponding to a keyhole, a key top, and a key sheet disposed between the key switch and the key top. An embossed portion recessed inwardly relative to a case body is formed on the key sheet in a state where the key sheet is pressed down by a pressing protuberance of the key top not depressed, and tip corner parts of the pressing protuberance contact the formed embossed portion. Thus, the key top can be naturally positioned in the center position of the keyhole.