A wind turbine generator capable of preventing a salt damage and reducing noise as well as easily starting in a cold region is provided. The wind turbine generator includes a nacelle (3) for accommodating a generator set, an internal heat exchanging unit (13, 15, 16) accommodated in the nacelle (3) to exchange heat between the generator set and a refrigerant, an external heat exchanging unit (17) disposed outside the nacelle (3) to exchange heat between an outside air and the refrigerant, a compressor (18) disposed in the nacelle (3) to compress the refrigerant and circulate the refrigerant between the internal heat exchanging unit (13, 15, 16) and the external heat exchanging unit (17), and an expansion unit (19) to expand the refrigerant compressed by the compressor (18).