The invention provides an air conditioner for a vehicle having a simple configuration and capable of controlling temperature in a wide range. In a dehumidification heating operation in which a refrigerant is circulated through a first heat exchanger, a second heat exchanger, an evaporator and a compressor in the order named so as to radiate the heat of the refrigerant into the first heat exchanger, there is provided a refrigerant heating means which heats the refrigerant when an outside air temperature is not higher than a predetermined temperature and when an opening degree of the second expansion valve which expands the refrigerant flowing out from the second heat exchanger is larger than an opening degree of the first expansion valve which expands the refrigerant flowing out from the first heat exchanger.