To provide a voltage regulator capable of maintaining the accuracy of an output voltage even if it is set to an arbitrary output voltage. A voltage regulator includes an output transistor comprised of an NMOS transistor having a backgate grounded, an error amplifier circuit configured to amplify and output a difference between a divided voltage obtained by dividing an output voltage outputted from the output transistor and a reference voltage and thereby to control a gate of the output transistor, a constant voltage circuit, and a transistor having a gate inputted with a voltage of the constant voltage circuit, a drain connected to the gate of the output transistor, and a source connected to a source of the output transistor.