A switching regulator is provided which can prevent overshooting in an output voltage even when a source voltage is returned to a normal voltage from a voltage lower than a desired output voltage of the switching regulator. The switching regulator includes a 100% duty detector circuit that detects that a PWM comparator is in a 100%-duty state and a discharge accelerator circuit that detects that the output of an error amplifier discharges the voltage of a phase compensating capacitor and that accelerates the discharge, and activates the discharge accelerator circuit when the 100% duty detector circuit detects the 100%-duty state.