A power supply device comprising: a power supply capable of supplying an electric power to a power supply line (PL1, PL2); a drive circuit (14, 31) arranged between said power supply line (PL1, PL2) and a motor (MG1, MG2) for driving and controlling said motor (MG1, MG2); a power storage device connected to said power supply line (PL1, PL2) and arranged in parallel to said power supply; a switch device (SRC1, SRC2) electrically connecting said power storage device to said power supply line (PL1, PL2) in a closed state; and a control device controlling an open/close operation of said switch device (SRC1, SRC2), wherein said power storage device includes: a relay circuit arranged to be connected in series to said switch device (SRC1, SRC2) on a current path being formed of said power supply line (PL1, PL2) and said power storage device when said switch device (SRC1, SRC2) is closed, and a removable first connection member adapted for being attached to said relay circuit for connecting contacts of said relay circuit together via a resistance element, and for being removed from said relay circuit for disconnecting the contacts of said relay circuit from each other, and wherein said control device is configured to close said switch device (SRC1, SRC2) in response to attachment of said first connection member to said relay circuit when a power supply voltage of said power storage device is equal to or lower than a predetermined threshold. a power supply capable of supplying an electric power to a power supply line (PL1, PL2); a drive circuit (14, 31) arranged between said power supply line (PL1, PL2) and a motor (MG1, MG2) for driving and controlling said motor (MG1, MG2); a power storage device connected to said power supply line (PL1, PL2) and arranged in parallel to said power supply; a switch device (SRC1, SRC2) electrically connecting said power storage device to said power supply line (PL1, PL2) in a closed state; and a control device controlling an open/close operation of said switch device (SRC1, SRC2), wherein said power storage device includes: a relay circuit arranged to be connected in series to said switch device (SRC1, SRC2) on a current path being formed of said power supply line (PL1, PL2) and said power storage device when said switch device (SRC1, SRC2) is closed, and a removable first connection member adapted for being attached to said relay circuit for connecting contacts of said relay circuit together via a resistance element, and for being removed from said relay circuit for disconnecting the contacts of said relay circuit from each other, and wherein said control device is configured to close said switch device (SRC1, SRC2) in response to attachment of said first connection member to said relay circuit when a power supply voltage of said power storage device is equal to or lower than a predetermined threshold. a relay circuit arranged to be connected in series to said switch device (SRC1, SRC2) on a current path being formed of said power supply line (PL1, PL2) and said power storage device when said switch device (SRC1, SRC2) is closed, and a removable first connection member adapted for being attached to said relay circuit for connecting contacts of said relay circuit together via a resistance element, and for being removed from said relay circuit for disconnecting the contacts of said relay circuit from each other, and wherein said control device is configured to close said switch device (SRC1, SRC2) in response to attachment of said first connection member to said relay circuit when a power supply voltage of said power storage device is equal to or lower than a predetermined threshold.