A semiconductor device according to related art has a problem that a clamp voltage that clamps an output voltage cannot adaptively vary in accordance with a power supply voltage, and it is thus not possible to reduce heating of a semiconductor chip to a sufficiently low level. According to one embodiment, a semiconductor device includes a drive circuit (10) that controls on and off of an output transistor (13) and an overvoltage protection circuit (12) that controls a conductive state of the output transistor (13) when an output voltage Vout reaches a clamp voltage, and the overvoltage protection circuit (12) has a circuit structure that sets the clamp voltage to vary in proportion to a power supply voltage VDD.