A vehicle air conditioner that can perform air conditioning operation in an inside air circulating mode while suppressing the mist on a windshield and prevent deterioration in an inside air quality. When exhaust gas concentration on the outside of a vehicle is high, an outside air lead-in mode is switched to an inside air circulating mode and window mist limit humidity at that point is calculated. When inside humidity is close to the window mist limit, a compressor is actuated, the air is blown out from a DEF blowout port into a cabin, or an air volume in a blower is increased to prevent the mist on the windshield and delay switching to the outside air lead-in mode as much as possible. Consequently, air conditioning operation in the inside air circulating mode is performed while the mist on the windshield is suppressed to prevent deterioration in the inside air quality.