A secondary battery device comprises: a first assembled battery (10(A)) including a plurality of secondary battery cells (BT); a second assembled battery (10(B)) including a plurality of the secondary battery cells (BT) and connected in series to a low voltage terminal of the first assembled battery (10(A)); a disconnection module (SD) for switching the connection between the first assembled battery (10(A)) and the second assembled battery (10(B)); a voltage measurement circuit (20) for measuring the voltages of the secondary battery cells (BT) in the second assembled battery (10(B)); first power supply wiring (W1) connected between a high voltage terminal of the second assembled battery (10(B)) and the voltage measurement circuit (20); second power supply wiring (W2) connected between a low voltage terminal of the second assembled battery (10(B)) and the voltage measurement circuit (20); and a filter (FL1) for short-circuiting between the first power supply wiring (W1) and the second power supply wiring (W2) at high frequency.
