Abstract: A heat pump system includes a refrigerant circuit in which a compressor, a refrigerant flow path included in a heat medium heat exchanger, an expansion valve, and a heat source side heat exchanger are connected, the heat medium heat exchanger including the refrigerant flow path and a heat medium flow path; a heat medium feed path connected to the heat medium flow path included in the heat medium heat exchanger; an indoor unit connected to the heat medium feed path and configured to condition air inside a room; a room temperature sensor configured to detect an indoor temperature in the room; a heat medium temperature sensor configured to detect a temperature of a heat medium that flows into the indoor unit; and a controller configured to control the refrigerant circuit or the indoor unit by using a set temperature in the room.