Abstract: Contacts connected to wires are set in a lower mold and an upper mold is then fitted on the lower mold. The upper and lower molds include contact restraining portions and wire restraining portions, and upper mold holding members and lower mold holding members extending into the cavity at opposite positions enabling these holding members to restrain the wires. The upper and lower molds further include elastic members arranged to urge the upper and lower mold holding members into the cavity of the upper and lower molds for restraining the wire before an insulating plastic material is poured into the cavity. Either of the upper and lower mold is provided with a contact positioning portion adapted to abut against distal ends of the contacts for positioning the contacts relative to the molds.