Abstract: A compact electronic apparatus comprises a casing of a wrist watch shape, a push button switch installed on the casing, waterproof packing being provided between the casing and the push button switch, a metal pipe mounted in the casing with its portion being extending out from the casing and including the push button switch therein, the metal pipe provided with a flange at its extending portion so as to form a recess, which recess is adapted to receive a mounting pipe of a release switch. The construction of the electronic apparatus allows a direct switching operation of the push button switch as well as a switching operation through the release switch. In either events, the casing of the present electronic apparatus is protected from water penetration with an extremely simple construct.