PURPOSE: To smoothly fill a cavity with a resin without making smaller a gate diameter by forming a trace of gate at the external circumference of a resin-sealed area.

CONSTITUTION: A gate 13 is provided at the one end side of a cavity 19 and is opposed to a lead wire 10. Moreover, resin flowing direction to the cavity 19 in the gate 13 is set to form a swirl along the internal circumferential surface of cavity 19 bypassing the lead wire 10. Therefore, the gate 13 can have sufficiently large diameter to lower the velocity of resin flowing through the gate 13 and ensure good flowing condition of resin into the cavity 19. Moreover, the lead wire 10 does not give any interference and can be cut or separated smoothly and a trace of gate 21 after the separation of lead wire is formed at the external circumferential surface of a sealing resin part 12. Accordingly, the trace of gate 21 can be processed easily by rotating the sealing resin part 12.