A heat pump system usable as an air-conditioning apparatus, a refrigerant apparatus, or a temperature-conditioning apparatus, having a heat capacity detection mechanism for detecting a signal indicative of a ratio of or a difference between the total heat-emitting capacity of the condenser and the total heat-absorbing capacity of the evaporator, and an energy-supplying mechanism for exerting energy onto the refrigerant, thereby compensating for insufficient total hear-absorbing capacity, especially in the cooling mode when condensation capacity increases due to, for example, a cold or wind environment.