To prevent the generation of burrs on the circumference of a lead part, when a resin sealing is performed using a transfer mold.

This lead frame is provided with a positive pole external lead 10a positioned on both ends of the lead frame, extended material parts 7 and 9 having a plurality of pieces which protrude in parallel with a middle rail and in the same direction outside a negative lead 10b and a supporting part 8. The extended material parts are pressed by a metal mold, and a resin sealing operation is performed using a transfer mold. Accordingly, even if there is a leakage of mold resin, it is stopped by the extended material parts 7 and 9 and the supporting part 8, and the resin burrs on the external lead part can be prevented from forming.