An assembled-battery voltage detection device for detecting a voltage at an assembled-battery including a plurality of single batteries connected in series includes: single-battery voltage detection circuits detecting voltages at the respective single batteries; single-battery voltage detection terminals connected to ends of the single batteries; connectors connecting the single-battery voltage detection terminals and the single batteries; voltage detection terminals detecting a voltage at one of the single batteries located at one end in the assembled battery; an assembled-battery voltage detection circuit detecting a potential difference between the voltage detection terminals; a single-battery voltage sum calculator calculating a sum of the voltages detected by the single-battery voltage detection circuits; an end-battery voltage abnormality determination unit determining whether the voltage at the single battery located at the end is 0 V; and an abnormality output unit outputting an abnormality depending on predetermined conditions.