A rotating electronic part has a board; a case composed of insulating resin; a supporting projection made of resin integrally structured with the case; and a rotating member. The board is provided with a central hole and three or more notches around the central hole at even angular intervals. The case fixes the board so as to maintain a penetration state of the central hole on the board. Each of the supporting projections is partially provided in one of the notches and projects to an inner radius of the central hole. The rotating member has a shaft inserted in the central hole on the board and is rotatably supported at the distal ends of the supporting projections; and a contact that faces to the board, makes a rotational movement with the rotation of the shaft, and contacts the board to output electric signals outward.