A battery monitoring device is configured to include a monitoring unit that transmits state information that indicates a state of a battery and that interrupts, using an interrupter, a power supply from a battery to a load upon receiving a power-interruption request or when a power supply to the monitoring unit is interrupted, and a controller that transmits a power-interruption request to the monitoring unit upon determining, on the basis of the state information transmitted from the monitoring unit, that an anomaly has occurred in the battery, wherein the controller interrupts, using an interrupter, a power supply to the monitoring unit upon determining that a communication anomaly has occurred between the monitoring unit and the controller, or that an anomaly has occurred in the monitoring unit.