When request power required of a power supply device by a driving force generation unit is close to zero, a converter ECU controls first and second converters to prohibit respective amounts of current passage in the first and second converters from simultaneously becoming close to zero. That is, when the request power is close to zero, the converter ECU performs voltage control of the first converter and sets an electric power control value for the second converter subjected to current control (electric power control) to a nonzero value, such that electric power is supplied and received between the first and second converters.