An air conditioner for a vehicle includes a pump that draws and discharges a heat medium, a cooler core that exchanges sensible heat between the heat medium and ventilation air into a vehicle interior to cool and dehumidify the ventilation air, a heat-medium and outside-air heat exchanger that exchanges sensible heat between the heat medium and outside air, a compressor adapted to draw and discharge a refrigerant in a refrigeration cycle, a heat-medium cooling heat exchanger that cools the heat medium by exchanging heat between a low-pressure side refrigerant in the refrigeration cycle and the heat medium, and first and second switching valves that switch between a first dehumidification mode for circulation of the heat medium between the cooler core and the heat-medium cooling heat exchanger and a second dehumidification mode for circulation of the heat medium between the cooler core and the heat-medium and outside-air heat exchanger.