Abstract: A strip of electroconductive material is perforated by I-shaped holes. Contact materials shaped to conform to said I-shaped holes are inserted in the holes and swaged. Then, the I-shaped contact materials are perforated across the middle thereof in conjunction with the adjoining portions of the electroconductive material so as to divide each contact material into two contacts separated by a contact gap formed therebetween. A leaf spring fitted at one end thereof with a movable contact intended for insertion into said contact gap is held in position, though not in an immobilized state, with the other end thereof simply inserted around the stem of a spring support. Terminals which are retained in their fixed relative position by means of a webbing interconnecting them are fastened with adhesive agent to a plastic case. After the fastening, said webbing is cut off.