Disclosed embodiments relate to a battery disconnect unit capable of being stably driven, and minimizing damage of a circuit, by including a means to protect the circuit at high temperatures without an additional power source. In some embodiments, the battery disconnect unit includes a first main relay electrically connected between a first pole of a battery and an inverter; a second main relay electrically connected between a second pole of the battery and the inverter; a pre-charge relay connected to the second main relay in parallel; and a self-operating switch connected between the first pole of the battery and the second main relay, and configured to autonomously open a circuit providing an electric power from the battery when a ambient temperature is drastically increased, or when an over-current occurs.