A method of manufacturing a semiconductor device, includes providing a lead frame including a frame portion, including a through hole penetrating the lead frame, a device forming portion surrounded by the frame portion in plan view, including a die pad, and a semiconductor chip mounted on the die pad; after the providing step, sealing the semiconductor chip with sealing resin by supplying the sealing resin to the device forming portion via a first region of the frame portion in which the through hole is formed in plan view, thereby forming a sealing body sealing the device forming portion and the first region of the frame portion; and after the sealing step, removing a first part of the sealing body located at the first region of the frame portion from the lead frame by inserting a pin into the through hole.