BATTERY MANAGEMENT UNIT

A battery management unit capable of more reliably turning off a high-voltage relay. A battery management unit includes a high-voltage relay serving as a switch unit that turns on/off electrical connection between a high-voltage battery , which is a secondary battery, and an external device, and a power source IC serving as a disconnection control unit having a first disconnection processing function of turning off the high-voltage relay at the time of abnormality of the battery management unit and a second disconnection processing function of detecting an abnormality of the first disconnection processing function and turning off the high-voltage relay