The present invention provides a heat pump including: a compressor; a radiator; a first throttling device having a variable opening; an expander; a second throttling device having a variable opening; an evaporator; piping that connects the compressor, the radiator, the first throttling device, the expander, the second throttling device, and the evaporator so that refrigerant circulates thorough the elements in that order; and a control device for controlling the opening of the first throttling device and the opening of the second throttling device. This heat pump is capable of independently controlling the pressure of the refrigerant flowing into the expander (intermediate pressure) and pressure in a high-pressure side of a refrigeration cycle, and also is capable of size reduction, or in some cases elimination, of a receiver for the refrigerant.