A power supply device comprising: a combination of one power supply module of a plurality of power supply modules configured to have different power supply performances and one controller of a plurality of controllers configured to have different functions, which are selectively combined, wherein each power supply module comprises a tray unit having a different number of stacked tray portions, each tray portion accommodating a plate-shaped power supply such as a capacitor, and a plate-shaped terminal portion, the capacitors are electrically connected in series via the plate-shaped terminal portions, and in each tray unit a first bus bar is connected to a tray lid portion stacked on the uppermost tray portion and is electrically connected to the plate-shaped terminal portion of the uppermost power supply via the capacitor, and a second bus bar is connected to a module bottom plate stacked below the lowermost tray portion and is electrically connected to the plate-shaped terminal portion of the lowermost plate-shaped power supply, wherein each of the plurality of power supply modules comprises a power supply module side connection portion common to the plurality of power supply modules and comprising the first and the second busbar, and each of the plurality of controllers comprises a controller side connection portion common to the plurality of controllers, comprises a first and a second bus bar hole (23c, 23d), and is configured to be connectable to the power supply module side connection portion, to allow that the one power supply module and the one controller are selectively combined, and for each power supply module the first and second bus bars (41, 52) protrude from the power supply module in the stacking direction and are configured to be fitted and electrically connectable to the first and second bus bar holes (23c, 23d) provided in a controller lid portion of each controller. a combination of one power supply module of a plurality of power supply modules configured to have different power supply performances and one controller of a plurality of controllers configured to have different functions, which are selectively combined, wherein each power supply module comprises a tray unit having a different number of stacked tray portions, each tray portion accommodating a plate-shaped power supply such as a capacitor, and a plate-shaped terminal portion, the capacitors are electrically connected in series via the plate-shaped terminal portions, and in each tray unit a first bus bar is connected to a tray lid portion stacked on the uppermost tray portion and is electrically connected to the plate-shaped terminal portion of the uppermost power supply via the capacitor, and a second bus bar is connected to a module bottom plate stacked below the lowermost tray portion and is electrically connected to the plate-shaped terminal portion of the lowermost plate-shaped power supply, wherein each of the plurality of power supply modules comprises a power supply module side connection portion common to the plurality of power supply modules and comprising the first and the second busbar, and each of the plurality of controllers comprises a controller side connection portion common to the plurality of controllers, comprises a first and a second bus bar hole (23c, 23d), and is configured to be connectable to the power supply module side connection portion, to allow that the one power supply module and the one controller are selectively combined, and for each power supply module the first and second bus bars (41, 52) protrude from the power supply module in the stacking direction and are configured to be fitted and electrically connectable to the first and second bus bar holes (23c, 23d) provided in a controller lid portion of each controller.