A vehicle air conditioner for supplementing and regulating the air volume discharged to front seats and rear seats through a door component that controls a passage, and enabling the length of a package in the direction of a heater core to be reduced. The vehicle air conditioner has an air passage comprising: a front seat air passage through which cold air or hot air is discharged toward the front seats of a vehicle; and a rear seat air passage through which cold air or hot air is discharged toward the rear seats of the vehicle, wherein the front seat air passage comprises a front seat cooling passage and a front seat heating passage, and the rear seat path comprises a rear seat cooling passage and a rear seat heating passage, and includes: a first mixing part in which the cold air of the front seat cooling passage and the hot air of the front seat heating passage are mixed; and a second mixing part in which the cold air of the rear seat cooling path and the hot air of the rear seat heating path are mixed.