A semiconductor device includes a drive circuit that outputs a drive signal to drive an external device; a voltage output circuit that outputs a first voltage and a second voltage that is larger than the first voltage; a selector that, when supplying a power supply voltage to the drive circuit, selects the first voltage and, when supplying a power supply voltage to an internal device, selects the second voltage; and a step-up circuit that, when the first voltage selected by the selector is input, boosts the first voltage to a third voltage and outputs the third voltage as the power supply voltage to the drive circuit and, when the second voltage selected by the selector is inputted, boosts the second voltage to a fourth voltage and outputs the fourth voltage as the power supply voltage to the internal device.