A direct-current power supply device includes a reactor, one end of which is connected to one output end of an alternating-current power supply, a switching unit for short-circuiting the other end of the reactor and the other output end of the alternating-current power supply, a rectifying unit configured to rectify an alternating-current voltage supplied from the alternating-current power supply and generate a voltage equal to or higher than a double voltage, a smoothing capacitor connected to the rectifying unit via backflow preventing diodes and configured to smooth a direct-current voltage output from the rectifying unit, and a control unit configured to control the switching unit and stop the supply of the alternating-current voltage to the rectifying unit in a predetermined period after a predetermined time has elapsed from a zero cross point of the alternating-current voltage output from the alternating-current power supply.