Power supply device provided with voltage detection unit

The present invention is provided with: an assembled battery (200) that is composed of N number of battery cells connected in series; (N+1) number of measurement lines (DL) that acquire analog signals corresponding to the terminal potential of the battery cells; a filter circuit (300) that attenuates a specified frequency component of the input analog signals and outputs same; and an analog/digital converter (460) that converts the analog signals output from the filter circuit (300) into digital signals. The filter circuit (300) is composed of: (N+1) number of input terminals (310); (N+1) number of output terminals (320); (N+1) number of filter resistors (340); and (N+1) number of filter capacitors (360) of which one end is connected between the filter resistors (340) and the output terminals (320) and the other ends are connected to each other in common.