A switching regulator is disclosed that is able to operate with low power consumption and able to prevent variation of an output voltage. The switching regulator operates in a PWM control mode and a PFM control mode, and includes a switching unit; an error amplification circuit for amplifying an error voltage between an output voltage and a first reference voltage; a slope circuit for generating a slope signal; a reference voltage generation circuit for generating a second reference voltage for determining a time interval of an ON state in the PFM control mode; a multiplexer for outputting one of the second reference voltage and an output voltage from the error amplification circuit; a comparison circuit for comparing an output voltage from the slope circuit to an output voltage from the multiplexer; and an oscillation circuit for determining a timing of the ON state in the PWM control mode.