A multiphase DC-DC converter that equalizes the output current of a plurality of converter units while improving responsiveness with respect to sudden changes in the output voltage. The converter includes a control unit for controlling the converter units. The control unit includes a comparator for comparing the output voltage of each of the converter units with a reference voltage, a first control circuit for sequentially selecting each of the converter units in accordance with an output signal of the comparator to activate the output transistor of the selected converter unit, and a second control circuit for controlling the inactivation timing of the output transistors of the converter units so as to equalize the output current of the converter units.