A voltage regulator has an output transistor that receives an input voltage inputted via an input terminal and that outputs a constant output voltage via an output terminal. A voltage divider circuit divides the output voltage to generate a divided voltage. A reference voltage circuit generates a reference voltage. An error amplifier circuit generates an error signal by comparing the divided voltage with the reference voltage. A protection circuit detects an abnormal state of the voltage regulator. A control circuit controls the output transistor to increase the output voltage to maintain the output voltage constant when an error signal is generated by the error amplifier circuit, and does not control the output transistor to increase the output voltage when the protection circuit detects an abnormal state of the voltage regulator.