According to one embodiment, a secondary battery device includes a first assembled battery including a plurality of secondary battery cells, a second assembled battery including a plurality of secondary battery cells and connected in series to a low-potential terminal of the first assembled battery, a disconnecting module capable of mechanically switching connection between the first assembled battery and the second assembled battery, a voltage measurement circuit configured to measure voltages of the plurality of secondary battery cells of the second assembled battery, a first power source wiring connected between a high-potential terminal of the second assembled battery and the voltage measurement circuit, a second power source wiring connected between a low-potential terminal of the second assembled battery and the voltage measurement circuit, and a filter connected between the first power source wiring and the second power source wiring.