BATTERY MONITORING DEVICE FOR VEHICLE-MOUNTED BATTERY

Provided is a battery monitoring device for a vehicle-mounted battery that can more accurately detect voltage in each location in the battery module and can protect a circuit if overcurrent and overvoltage occur. In the battery monitoring device for the vehicle-mounted battery, a power source line is electrically connected to a high voltage electrode portion, and is a path through which current flows from a high voltage electrode portion side without passing through a first fuse (first current interruption unit) of the high voltage signal line. The second Zener diode has a cathode that is electrically connected to the power source line and an anode that is electrically connected to another one of the plurality of high voltage signal lines than the high voltage signal line.