PURPOSE: To prevent damages in the wire of a diode during the period of molding a resin sealing part.

CONSTITUTION: Both side peripheral parts in the wire fitting groove 16 of an upper mold member 11 are shaped into a curved part 21 being curved smoothly in its almost circular section. The almost semicircular sectional wire fitting groove 17 of a lower mold member 12 is positioned higher than the parting line surface 12a in its central part of the sectional configuration. Both side peripheral parts in the wire fitting groove 17 of the lower mold member 12 are shaped into a curved part 21 being smoothly in its almost circular section. In this manner, even if both mold members 11, 12 do not transversely meet each other, the side periphery of the wire fitting groove 16 is hard to bite in the wire 2 during the mold clamping period because of the existence of the curved part 21. Even when the wire 2 is raised up from the wire fitting groove 17, the wire 2 is pushed smoothly into the wire fitting groove 17 following the mold clamping.