A semiconductor device according to an embodiment includes: a bonding substrate which includes a first chip forming portion having first metal pads provided at a semiconductor substrate and a first circuit connected to the first metal pads, and a second chip forming portion having second metal pads joined to the first metal pads and a second circuit connected to the second metal pads and being bonded to the first chip forming portion; and an insulating film which is filled into a non-bonded region between the first chip forming portion and the second chip forming portion at an outer peripheral portion of the bonding substrate. At least a part of the insulating film contains at least one selected from the group consisting of silicon nitride and nitrogen-containing silicon carbide.