A resin molded type semiconductor device has: a semiconductor chip (12) which is mounted on a die pad portion (11) of a lead frame (9); thin metal wires (14) which connect terminals of the semiconductor chip (12) to inner lead portions (13) of the lead frame (9); and a sealing resin (15), and the lead frame (9) is subjected to an upsetting process so that a supporting portion (11) is located at a position higher than the inner lead portions (13). Since the sealing resin of a thickness corresponding to the step difference of the upsetting exists below the supporting portion, the adhesiveness between the lead frame and the sealing resin can be improved, and high reliability and thinning are realized. Since at least one groove portion is disposed in the surface of each of the inner lead portions (13), the anchoring effect to the sealing resin (15), stress acting on a lead portion of a product, and stress to the thin metal wires (14) can be relaxed, and leads and the thin metal wires can be prevented from peeling off.