Improvement of responsiveness and stability of room temperature are achieved by learning each of a heat transfer characteristic of a building and a heat medium utilization apparatus characteristic from operation data even when, for example, a heat medium utilization apparatus to be connected is unknown. A control command determiner (52) includes an output water temperature command reference value determiner (56) configured to determine an output water temperature command reference value on the basis of a building characteristic (58) and a heat radiation apparatus characteristic (59) that are learned by a characteristic calculator (53), an outside air temperature, and a set temperature, and an output water temperature command correction value determiner (57) configured to determine an output water temperature command correction value on the basis of a correction coefficient, the set temperature, and an indoor temperature. The control command determiner (52) is configured to determine a control command for a water air-conditioning system (1) by adding the output water temperature command correction value to the output water temperature command reference value.