A battery charger for charging a battery pack having a battery, a temperature sensor for sensing a temperature of the battery, and a battery terminal. The battery charger includes a charger terminal to which the battery terminal is connected when the battery is charged, a charge current generating circuit that generates a charge current for charging the battery, a battery temperature detector, and a controller. The battery temperature detector is configured to include a circuit, for example, to detect a temperature of the battery while cooperating with the temperature sensor and to output a temperature signal indicative of the temperature of the battery. The controller which is supplied with the temperature signal from the battery temperature detector, corrects the temperature signal, and provides a corrected temperature signal.