A semiconductor device with a thickness of 1 mm or less is disclosed, that comprises a frame plate main body with a thickness in the range from 0.1 mm to 0.25 mm, a semiconductor pellet disposed on a first surface of the frame plate main body and with a thickness in the range from 0.2 mm to 0.3 mm, an external connection lead, one end thereof being connected to a peripheral portion of the first surface of the frame plate main body, the other end thereof extending to the outside of the frame plate main body, a bonding wire for electrically connecting an electrode of the semiconductor pellet and a connection portion of the end of the external connection lead, and a sealing resin layer for covering and sealing at least a region including the semiconductor pellet, the bonding wire, and a connection portion.