A DCDC converter includes a control circuit, a transistor in which switching is controlled by being supplied voltage output from the control circuit to a gate electrode of the transistor, a voltage conversion portion in which supply of input voltage is controlled by the switching of the transistor and output power commensurate with duty ratio of the switching of the transistor, and a detection circuit detecting the output power. Further, the control circuit includes a control signal generation circuit generating a control signal with a pulse voltage waveform and a selection circuit applying voltage of the control signal to the gate electrode in the case where current detected by the detection circuit is the same as or exceeds the threshold value and applying voltage for turning on the transistor to the gate electrode in the case where the current detected by the detection circuit falls below the threshold value.