PURPOSE: To attain simplification of equipment and manufacture at low cost of the device by a method wherein the base of a package is premolded in one body with a lead member using a thermoplastic member, a semiconductor element pellet is fixed to the lead member through a concave part provided in the base thereof, and after the prescribed electric connection is performed, they are sealed with resin to construct the device.

CONSTITUTION: The lead frame 11 formed by punching a metal plate material has the central tab 4 and the leads 3 of the plural pieces arranged at the circumference thereof, and they are connected by a frame 12. Then the base 2 to be premolded to the lead frame 11 thereof is molded removing the upper part of the tab 4 and the wire post parts 3a to form the concave part 6. Then the semiconductor element pellet 5 is fixed on the exposed tab 4 using Ag paste 7, and the wire post parts 3a of the leads 3 exposing the same and the pellet 5 are connected with the wires 8. After the pellet 5 is built in by this way, low viscosity resin 9 is flowed in to be filled up in the concave part 6 to form as a cap, the pellet 5 and the wires 8 are sealed and fixed to be integrated in one body with the base 2, and the package is completed.