A switching regulator for inputting a power source, supplying output power to an external circuit, and adjusting the output voltage to a target voltage, the switching regulator has a switching regulator circuit having first and second transistors, a feedback circuit that receives the output voltage, and outputs a control pulse signal at a frequency in accordance with the received output voltage; a PLL circuit unit having a PLL circuit, and a first control signal generating circuit that outputs the first control signal for controlling the first transistor; and a drive circuit that outputs a second control signal that controls the second transistor; and a control circuit that monitors the period of the PLL output pulse and the control pulse signal, and controls the ON and OFF timing of the second transistor when a difference of monitored periods.