A compressor, a radiator, an expander, and an evaporator are connected in series to define a refrigerating cycle. A bypass circuit that bypasses the expander, an on-off valve disposed in the bypass circuit, and a controller C1 for controlling an opening of the on-off valve are provided in the refrigerating cycle. During defrosting, the controller C1 controls the on-off valve so that a refrigerant may flow through the bypass circuit, thereby avoiding reduction in the amount of flow of the refrigerant during defrosting and preventing the defrosting operation from being prolonged.