Air conditioner for use in vehicles

An air conditioner for use in vehicles includes a compressor (11) that is connected to an engine (1) for driving a vehicle and operated by a driving force provided by the engine (1) during operation of the engine (1). Connection between the engine (1) and the compressor (11) is released in response to stopping of the engine (1), and an electric motor (14) for driving the compressor (11) is connected to the compressor (11) in response to stopping of the engine (1). The compressor (11) is operated by the electric motor (14) during stopping of the engine (1).