A semiconductor device includes a header, a semiconductor chip fixed to the header constituting a MOSFET, and a sealing body of insulating resin which covers the semiconductor chip, the header and the like, and further includes a drain lead contiguously formed with the header and projects from one side surface of the sealing body, and a source lead and a gate lead which project in parallel from one side surface of the sealing body, and wires which are positioned in the inside of the sealing body and connect electrodes on an upper surface of the semiconductor chip and the source lead and the gate lead, with a gate electrode pad arranged at a position from the gate lead and the source lead farther than a source electrode pad.