A voltage regulator having good transient response characteristics and maintaining stable operation is provided. The voltage regulator includes: a first MOS transistor having a gate terminal connected to an output terminal of the differential amplifier circuit; a first constant current source provided between the first MOS transistor and a ground terminal; an output MOS transistor having a gate terminal connected to a drain terminal of the first MOS transistor via a phase compensation circuit; a second MOS transistor having a gate terminal to which an output of the differential amplifier circuit is input and a drain terminal connected to the gate terminal of the output MOS transistor; and a second constant current source provided between the second MOS transistor and a ground terminal.