An air conditioner for a vehicle includes: a pump configured to take in and discharge a heat medium; a first heat medium/air heat exchanger disposed to regulate a temperature of ventilation air blown into a vehicle interior by conducting sensible-heat exchange between the ventilation air and the heat medium circulated by the pump; a first heat transfer device having a passage through which the heat medium flows and disposed to conduct heat transfer with the heat medium circulated by the pump; a heat medium temperature regulator disposed to regulate the temperature of the heat medium circulated by the pump; and a heat exchanger regulator disposed to regulate a heat transfer amount with the heat medium in the first heat transfer device or heat exchange capability of the first heat medium/air heat exchanger such that a temperature associated with a temperature of the ventilation air regulated by the first heat medium/air heat exchanger approaches a first target temperature.