PURPOSE: To make the inside of a room difficult to reach the combustion lower limit concentration by being capable of gathering refrigerant in a refrigerant circuit at the outdoor side in a short time even at the time of driving cooling or heating and delaying the leakage speed to the refrigerant chamber as low as possible when the refrigerant is leaked at the indoor side of the refrigerant circuit.

CONSTITUTION: A storage unit is arranged at a bypass tube 10 connected at its one end to a tube 6 between a four-way switching valve 5 and an outdoor side heat exchanger 2 via a first three-way valve 11 and at the other to a tube 6 between an indoor side heat exchanger 4 and a four-way switching valve 5 via a second three-way valve 12. The first and second valves 11, 12 are so controlled to be switched by switch control means 40 as to store the refrigerant in a refrigerant circuit 7 in the storage unit 20 when leakage detecting means 30 detects the leakage of the refrigerant.