To increase a system structure, easily meet lubricating oil and simplify an operation control.

A primary side circuit 20 in which a primary side refrigerant as a heat source and a secondary side circuit 30 in which a secondary side refrigerant circulates are provided. A regenerative circuit 40 connected to the secondary side circuit 30 is provided so that the secondary side refrigerant circulates. Then, is carried out at least a regenerative operation in which the secondary side refrigerant circulates between the regenerative circuit 40 and a main heat exchanger 11 to store heat, a stored heat using operation in which the secondary refrigerant circulates between the regenerative circuit 40 and an indoor heat exchanger to perform an air conditioning and an ordinary operation in which the secondary side refrigerant circulates the secondary side circuit 30 to perform an air conditioning.