PURPOSE: To improve a reliability in control for preventing liquid refrigerant from flowing into a compressor.

CONSTITUTION: In the case that it is assumed that a difference between a temperature (t0) of a casing of a compressor and a refrigerant temperature (t1) of an indoor heat exchanger 5 (evaporator) get a relation of (t0-t1)≤T during a cooling operation, for example, the liquid refrigerant approaches a state where it may easily flow into the compressor 1. In such a case as above, a control means 11 decreases the number of rotation of an outdoor fan 12 in response to a discriminating signal from a temperature difference discriminating means 10. Then, a heat exchanging efficiency of an outdoor heat exchanger 3 is decreased, so that an amount of condensation is decreased and almost of all refrigerant are evaporated at the outdoor heat exchanger. Accordingly, the liquid refrigerant is prevented from being flowed into the compressor 1. After this operation, the value (t0-t1) is increased again due to an increasing of a discharging pressure at the compressor 1.