A power supply device 100 comprises a plurality of power storage devices 10 connected in parallel, and includes an NTC 40 that detects a temperature of each of the plurality of power storage devices 10, an FET 21/22 connected to each of the plurality of power storage devices in series, and a control unit that controls ON and OFF states of the FET 21/22. The control unit performs a temperature control to increase a time ratio of the OFF state in controlling the ON and OFF states of the FET 21/22 based on the temperature detected by the NTC 40. Thus, a power supply device and an electric vehicle that can restrain shortening of the life duration of the device as a whole can be provided by restraining increase and variation of the temperature of each power storage device.