The purpose of the present invention is, in multiphase interleave control of a power supply device, to suppress the occurrence of overshoot and undershoot of output voltage, and have control for whichthe number of detection units and a control system are not dependent on the number of phases. In power control of the power supply device for which deadbeat control is applied to multiphase interleaving, in multiphase control using multiphase interleaving, by using a combined current of phase currents of multiple phases as the control current, control is realized for which the number of detectionunits and the control system are not dependent on the number of phases, and by performing constant current control using the control current, the occurrence of overshoot and undershoot is suppressed.The power supply device has multiphase interleave control with which multiphase control is performed using a plurality of phase currents, and is provided with an LC chopper circuit configuring a voltage dropping chopper circuit that is operated using multiphase control of multiphase interleaving, and a control unit that controls the step response using multiphase control of the LC chopper circuit.