To provide a voltage regulator having quick responsiveness in low power consumption and allowed to be stably driven by low output capacity.

The voltage regulator comprises a differential amplifier for comparing the output of a reference voltage circuit with the output of a voltage dividing circuit and outputting a 1st signal, a phase compensation circuit in which a resistor and a capacitor are connected in series, a MOS transistor capable of inputting the output of the differential amplifier to a gate electrode, connected between a power supply and the phase compensation circuit and connecting a source to ground, a constant current circuit connected between the MOS transistor and the ground, and an output transistor capable of inputting a 2nd signal outputted from a node between the MOS transistor and the phase compensation circuit to a gate electrode and connected between the power supply and the voltage dividing circuit. The resistor side of the phase compensation circuit is connected to the output of the differential amplifier circuit and the capacitor side of the phase amplifier circuit is connected to the drain electrode of the MOS transistor.