In a vehicle air conditioner, a heater core is disposed in an air conditioning case to form front and rear cool air bypass passage through which cool air bypasses the heater core, and front and rear air mixing doors are disposed to independently adjust temperature of air blown toward a front seat side and temperature of air blown toward a rear seat side in a passenger compartment. A switching door is disposed to partition front and rear passage portions of the heater core from each other at a partition position, and to shut the rear passage portion at a rear shutting position. The switching door and the rear air mixing door are connected to a common operation mechanism to be operatively linked with each other.