PURPOSE: To perform air conditioning control (temperature control) even in the rear seat side of a vehicle independently of the front seat side.

CONSTITUTION: An air conditioning unit 1 for a front seat of a vehicle comprises a blower unit 2 having a sirocco fan 7, cooler unit 3 having an evaporator 8 and a heater unit 4 having a heater core 9 and an air mix damper 10. A rear unit 24 provides a rear duct 25 to which cold air from the cooler unit 3 is partly introduced through a communication duct 26. A fan 28, heater core 29, air mix damper 30, face blow port damper 31 and a foot blow port damper 32 are arranged in the rear duct 25. In accordance with opening/closing conditions of the air mix damper 30, mixing ratio of a hot air amount from the heater core 29 to a cold air amount from the fan 28 is adjusted, and a flow of air thus temperature-controlled is supplied to both or only one of a rear face duct 33 and a rear foot duct 34.