Abstract: A waterproof case for receiving a circuit board includes a housing, a cover and a waterproof washer. The inner edge of the opening end of the housing is formed into a slant inner edge, and a closed end of the housing is provided with supporting members for supporting the circuit board. The cover is attached to the opening end of the housing, and has an annular flange for mounting the waterproof washer, mounting members for mounting the circuit board, and a through hole for wires. When fixing the cover onto the housing by appropriate fastening members, the waterproof washer will be pushed by the cover and abut against the slant inner edge, and thereby achieve the seal between the cover and the housing.