A refrigerating cycle apparatus is used in an air-conditioning system of an automotive vehicle, which is capable of operating in a hot gas bypass heating mode. Here, the discharge side of a compressor is directly connected through a hot gas bypass conduit to the inlet side of an evaporator. The evaporator acts as a radiator, heated by gas refrigerant. The compressor is stopped during operation of the apparatus in this heating mode when a physical quantity representing the high-side pressure at the compressor discharge side rises above a set value. The compressor is restarted when a physical quantity representing a heating capacity (for example the high-side pressure) falls below a set value which indicates that there is no heating capacity in the stopped state of the compressor. As a result, the heating capacity obtained through hot gas bypass can be controlled well without frequent stopping and restarting of the compressor.