A semiconductor device is provided, including a semiconductor substrate, wherein the semiconductor substrate has: a diode region; a transistor region; and a boundary region that is positioned between the diode region and the transistor region, the boundary region includes a defect region that is provided: at a predetermined depth position on a front surface-side of the semiconductor substrate; and to extend from an end portion of the boundary region adjacent to the diode region toward the transistor region, at least part of the boundary region does not include a first conductivity-type emitter region exposed on a front surface of the semiconductor substrate, and the transistor region does not have the defect region below a mesa portion that is sandwiched by two adjacent trench portions, and closest to the boundary region among the mesa portions having the emitter region.