Abstract: The operating key switch unit according to the present invention includes a plurality of key switch buttons exposed from the front of a waterproof case and a switch panel integrally formed therein using an elastic material and mounted with bolts between the waterproof case and a printed circuit board. Furthermore, a first contactor projecting in the key switch button operating direction annularly in a surrounding relation to the key switch buttons is provided, and a second annular contactor formed integrally with the switch panel and in contact with the first contactor throughout the overall circumference at all times is provided.