PURPOSE: To provide a device, which is easy to control and has the excellent reliability in homogenization in mass production, by eliminating problem areas occurring each step when a lead and an insulating sheet are bonded and a semiconductor element and the insulating sheet are bonded.

CONSTITUTION: A semiconductor element 12 and a lead 8, which is connected to the element, are fixed. through an insulating sheet 9, on both front and rear surfaces of which a bonding agent is applied, in a semiconductor device. In this semiconductor device, a sheet, on one surface of which a thermosetting-resin bonding agent 10 is applied, and on the other surface of which a bonding agent comprising a thermoplastic-resin bonding agent 11 is applied, is used as the insulating sheet 9.