An air conditioning device for a vehicle having a regenerative section improves efficiency of regeneration. The air conditioning device comprises a compressor (6) connected to an output shaft (1a) of an engine (1) via an electromagnetic clutch (5), a motor-generator (2) for electrically recovering kinetic energy of the vehicle (100) during deceleration, a battery (9) for storing energy regenerated by the motor-generator (2), and a motor-driven compressor (13). When the vehicle (100) is in a deceleration state, the compressor (6) is disconnected from the engine (1) by disengaging the electromagnetic clutch (5), and air conditioning is performed by the motor-driven compressor (13).