Abstract: An electronic apparatus includes a case body having an opening in an upper side thereof, an annular groove provided on the outer periphery of the opening and an engaging hole in a portion of the case above the annular groove, an annular sealing ring inserted into the annular groove, a frame for supporting printed circuit boards on which electronic circuitry is mounted, the frame being formed to include a terminal base provided on the side of the opening of the case body, and having a resilient projection for mating with the engaging hole of the case body from an inner side thereof, and a main body cover provided with an inwardly directed projection for mating with the engaging hole of the case body from an outer side thereof, the main body cover covering the opening by mating the projection with the engaging hole of the case body.