Disclosed is an assembled battery (10) constituted to have a plurality of secondary batteries (2) connected in series and to comprise a first bypass circuit (12) including a Zener diode (6) connected in parallel with the series connection and in a direction to be inversely connected at a charging time, and a second bypass circuit (14) including a varistor (4) connected in parallel with the secondary batteries (2) and the Zener diode (6). The Zener diode (6) has a Zener voltage set at a predetermined first voltage value, and the varistor (4) has a varistor voltage set at a second voltage value equal to or higher than the first voltage value.