To provide a semiconductor device which can achieve low resistance by a thinned silicon carbide substrate, and a manufacturing method thereof.

According to one embodiment, a semiconductor device comprises: a silicon carbide substrate; a semiconductor layer; an insulation film; a reinforcement substrate; a first electrode; and a second electrode. The semiconductor layer is provided on a second surface of the silicon carbide substrate and has an element region and a peripheral region closer to an end side than to the element region. The insulation film is provided on a surface of the peripheral region of the semiconductor layer. The reinforcement substrate is provided on the insulation film in the peripheral region. The first electrode is provided in contact with a first surface of the silicon carbide substrate. The second electrode is provided in contact with a surface of the element region.