A power supply system capable of supplying an electric power to a load device, comprising: a chargeable and dischargeable power storage device; a power line (MPL, MNL) configured to be capable of supplying and receiving the electric power between the power supply system and said load device; a converter arranged between said power storage device and said power line (MPL, MNL) for performing voltage conversion between said power storage device and said power line ( MPL, MNL); a chargeable and dischargeable power storage unit connected to said power line (MPL, MNL), said power storage unit being a smoothing capacitor reducing an electric power variation component of said power line ( MPL, MNL); a control device controlling said converter by setting a predetermined target value; and a voltage sensor sensing a voltage on said power line ( MPL, MNL), wherein during temperature rise control for raising a temperature of at least one of said power storage device and said power storage unit, said control device sets said target value such that said converter passes the electric power from said power storage device through said power line (MPL, MNL) to said power storage unit when the voltage sensed by said voltage sensor reaches a lower limit value, and sets said target value such that said converter passes the electric power from said power storage unit through said power line (MPL, MNL) to said power storage device when said sensed voltage reaches an upper limit value, characterized in that said upper and lower limit values are set according to a state of said power storage device, and said upper and lower limit values are set to larger values as the temperature of said power storage device lowers or a state quantity representing a state of charge of said power storage device decreases. a chargeable and dischargeable power storage device; a power line (MPL, MNL) configured to be capable of supplying and receiving the electric power between the power supply system and said load device; a converter arranged between said power storage device and said power line (MPL, MNL) for performing voltage conversion between said power storage device and said power line ( MPL, MNL); a chargeable and dischargeable power storage unit connected to said power line (MPL, MNL), said power storage unit being a smoothing capacitor reducing an electric power variation component of said power line ( MPL, MNL); a control device controlling said converter by setting a predetermined target value; and a voltage sensor sensing a voltage on said power line ( MPL, MNL), wherein during temperature rise control for raising a temperature of at least one of said power storage device and said power storage unit, said control device sets said target value such that said converter passes the electric power from said power storage device through said power line (MPL, MNL) to said power storage unit when the voltage sensed by said voltage sensor reaches a lower limit value, and sets said target value such that said converter passes the electric power from said power storage unit through said power line (MPL, MNL) to said power storage device when said sensed voltage reaches an upper limit value, characterized in that said upper and lower limit values are set according to a state of said power storage device, and said upper and lower limit values are set to larger values as the temperature of said power storage device lowers or a state quantity representing a state of charge of said power storage device decreases.