To obtain a semiconductor device provided with a plurality of protrusions for regulating the thickness of a bonding part on the rear surface side pattern of an insulating substrate or a base plate in which reliability is enhanced by suppressing thermal stress in the bonding part located at the circumferential edge of the rear surface side pattern of an insulating substrate or on the periphery of the end part of the protrusion thereby enhancing crack resistance of a bonding material.

A rear surface side pattern of an insulating substrate or a base plate is provided with a plurality of protrusions for regulating the thickness at the bonding part of the rear surface side pattern and the base plate. An end part of the protrusion facing the circumferential edge of the rear surface side pattern is located in a region spaced apart by 1-10 mm from the circumferential edge and the bonding part is formed thicker in a region spaced apart by 1 mm inward from the position facing the circumferential edge of the rear surface side pattern as compared with other regions.