A power supply device comprising: a multi-phase converter including first and second chopper circuits (13-1, 13-2) connected in parallel and connectable between a power supply line connected to a load and a power supply of direct current, said first chopper circuit including a first switching circuit (Q11, Q12) and a first reactor disposed to pass electric current in response to operation of said first switching circuit (Q11, Q12), said second chopper circuit including a second switching circuit (Q21, Q22) and a second reactor disposed to pass electric current in response to operation of said second switching circuit (Q21, Q22), said first reactor and said second reactor being arranged to be magnetically coupled to each other; and a control circuit including: a setting unit configured to set a voltage command value for said power supply line based on an operating state of said load; and a control unit (310, 320, 325, 330, 350) configured to control said first chopper circuit and said second chopper circuit; characterized by a first sensor configured to detect a value of current flowing in said first reactor; and a second sensor configured to detect a value of current flowing in said second reactor; said control circuit configured to control, in a case of a low-temperature state in which a temperature of said power supply is lower than a predetermined value, said first and second chopper circuits (13-1, 13-2) so that a difference between the value of current flowing in said first reactor and the value of current flowing in said second reactor is increased relative to a ase of a non-low-temperature state in which the temperature of said power supply is higher than said predetermined value, to thereby increase a ripple component of current flowing in said power supply, said control unit (310, 320, 325, 330, 350) configured to control said first chopper circuit (13- 1) in accordance with a result of a first calculation performed based on said voltage command value and the value detected by said first sensor and controlling said second chopper circuit in accordance with a result of a second calculation performed based on said voltage command value and the value detected by said second sensor, and said control unit (310, 320, 325, 336, 350) being configured to perform, an offset process of adding a predetermined amount to the value detected by one of said first sensor and said second sensor to thereby increase a difference between the value of current flowing in said first reactor and the value of current flowing in said second reactor. a multi-phase converter including first and second chopper circuits (13-1, 13-2) connected in parallel and connectable between a power supply line connected to a load and a power supply of direct current, said first chopper circuit including a first switching circuit (Q11, Q12) and a first reactor disposed to pass electric current in response to operation of said first switching circuit (Q11, Q12), said second chopper circuit including a second switching circuit (Q21, Q22) and a second reactor disposed to pass electric current in response to operation of said second switching circuit (Q21, Q22), said first reactor and said second reactor being arranged to be magnetically coupled to each other; and a control circuit including: a setting unit configured to set a voltage command value for said power supply line based on an operating state of said load; and a control unit (310, 320, 325, 330, 350) configured to control said first chopper circuit and said second chopper circuit; characterized by a setting unit configured to set a voltage command value for said power supply line based on an operating state of said load; and a control unit (310, 320, 325, 330, 350) configured to control said first chopper circuit and said second chopper circuit; a first sensor configured to detect a value of current flowing in said first reactor; and a second sensor configured to detect a value of current flowing in said second reactor; said control circuit configured to control, in a case of a low-temperature state in which a temperature of said power supply is lower than a predetermined value, said first and second chopper circuits (13-1, 13-2) so that a difference between the value of current flowing in said first reactor and the value of current flowing in said second reactor is increased relative to a ase of a non-low-temperature state in which the temperature of said power supply is higher than said predetermined value, to thereby increase a ripple component of current flowing in said power supply, said control unit (310, 320, 325, 330, 350) configured to control said first chopper circuit (13- 1) in accordance with a result of a first calculation performed based on said voltage command value and the value detected by said first sensor and controlling said second chopper circuit in accordance with a result of a second calculation performed based on said voltage command value and the value detected by said second sensor, and said control unit (310, 320, 325, 336, 350) being configured to perform, an offset process of adding a predetermined amount to the value detected by one of said first sensor and said second sensor to thereby increase a difference between the value of current flowing in said first reactor and the value of current flowing in said second reactor.