A flying capacitor type voltage detecting device which uses a capacitor to detect a voltage of each battery stack of a battery pack which includes a plurality of battery stacks each of which includes a plurality of battery cells connected in series, includes: a detecting unit that detects a voltage between both ends of the capacitor, as the voltage of each battery stack; and a branch line that is a single line which is branched from a connection line connecting the battery stacks and the detecting unit and connected to the capacitor and where a current during charging of the capacitor and a current during discharging of the capacitor flow in opposite directions.