A power supply device includes a board that includes an input terminal and an output terminal, and converters disposed on the board. The converters are connected with each other in parallel and convert an input voltage input to the input terminal, and output the converted voltage to the output terminal. Each of the converters includes respective one of voltage conversion functional units including respective one of input parts and respective one of output parts, respective one of input line parts connected to respective one of the input parts. Respective one of output line parts connected to respective one of the output parts, and respective one of current adjustment functional units provided in respective one of the output line parts for balancing currents output from the each of the converters provided in respective one of the output line parts.