A battery pack including a protection circuit configured to detect over-charge, over-discharge and over-current of a rechargeable battery to turn off a switch element, the switch element provided at a wire provided between the rechargeable battery and a load circuit or a charging device; a series circuit of a thermistor and a resistor, the series circuit provided in parallel to the rechargeable battery, the thermistor thermally connected to the rechargeable battery; and an abnormal temperature detection unit provided in the protection circuit, wherein the abnormal temperature detection unit operates the switch to be in an off state when the temperature of the rechargeable battery is higher than a predetermined temperature, and when a voltage of the wire is higher than a threshold voltage of a forward drop voltage of a body diode in the switch, the abnormal temperature detection unit operates the switch to be in an on state.