A semiconductor device, including a semiconductor substrate, a transistor section and a diode section arranged in a predetermined arrangement direction and provided on the semiconductor substrate, is provided. The diode section includes a drift region of a first conductivity-type provided in the semiconductor substrate, a base region of a second conductivity-type extending to a height of an upper surface of the semiconductor substrate and provided above the drift region, first cathode regions of the first conductivity-type, and second and third cathode regions of the second conductivity-type. The first, second, and third cathode regions extend to a height of a lower surface of the semiconductor substrate in a depth direction and provided below the drift region. The first and second cathode regions are provided in contact with each other, alternating in the arrangement direction, and sandwiched between the third cathode regions in an extension direction orthogonal to the arrangement direction.