A breakdown voltage structure portion includes a field plate with an annular polysilicon field plate and a metal field plate. In the breakdown voltage structure portion, a plurality of annular guard rings are provided in a surface layer of the semiconductor substrate. The polysilicon field plates are separately arranged on the inner circumferential side and the outer circumferential side of the guard ring. Polysilicon bridges that connect the polysilicon field plates on the inner and outer circumferential sides are provided on at least one guard ring among the plurality of guard rings at a predetermined interval so as to be arranged over the entire circumference of the guard ring. The metal field plate is provided on the guard ring in a corner portion of the breakdown voltage structure portion and at least one guard ring in a straight portion of the breakdown voltage structure portion.