An objective of the present invention is to miniaturize a connector for connecting an exchangeable battery to an electric vehicle. A power supply device includes a first battery which is exchangeable and includes a battery connector for connection to a moving object; a moving object connector disposed at the moving object and connectable to the battery connector; a first power converting section connected between the moving object connector and a load; a second battery connected to a power supply line in parallel to the first battery, wherein the power supply line is configured to connect the first power converting section to the load; and a control section which is configured to control the first power converting section in such a way that a current which is output from the first battery to the first power converting section via the moving object connector has a first value or a smaller value.