A control device for controlling a plurality of heat pump devices (20a1, 20a2,..., 20a(n-1), 20an) which are disposed in order in a circulation path to vary a temperature of circulating water, and which include a most downstream heat pump device disposed furthest downstream in the circulation path, the control device comprising: a temperature variation control unit for performing control for varying the temperature of the water, on the basis of a variation amount of a water temperature in a facility, equipment capacity of each of the heat pump devices, a target outlet water temperature in each of the heat pump devices, an actually measured value of an inlet water temperature of each of the heat pump devices, and an actually measured value of an outlet water temperature of each of the heat pump devices; a variation amount reading unit for reading the variation amount which varies the temperature of the water in all of the plurality of heat pump devices (20a1, 20a2,..., 20a(n-1), 20an) from a storage unit; a variation amount allocation determining unit for equally dividing the variation amount read from the storage unit by the variation amount reading unit by the number of the plurality of heat pump devices, at the normal time, and determines a variation amount of water temperature to be allocated to the plurality of heat pump devices (20a1, 20a2,..., 20a(n-1)) other than the most downstream heat pump device such that the variation amount to be allocated to the most downstream heat pump device is smaller than the variation amount at the normal time, at a predetermined timing; and characterized in that the variation amount allocation determining unit is configured to determine the variation amount to be allocated to the plurality of heat pump devices (20a1, 20a2,..., 20a(n-1)) other than the most downstream heat pump device such that the variation amount to be allocated to the most downstream heat pump device at a predetermined timing is smaller than the variation amount at the normal time when the variation amount allocation determining unit determines that a target temperature of the water at output of the most downstream heat pump device exceeds a first set temperature. a temperature variation control unit for performing control for varying the temperature of the water, on the basis of a variation amount of a water temperature in a facility, equipment capacity of each of the heat pump devices, a target outlet water temperature in each of the heat pump devices, an actually measured value of an inlet water temperature of each of the heat pump devices, and an actually measured value of an outlet water temperature of each of the heat pump devices; a variation amount reading unit for reading the variation amount which varies the temperature of the water in all of the plurality of heat pump devices (20a1, 20a2,..., 20a(n-1), 20an) from a storage unit; a variation amount allocation determining unit for equally dividing the variation amount read from the storage unit by the variation amount reading unit by the number of the plurality of heat pump devices, at the normal time, and determines a variation amount of water temperature to be allocated to the plurality of heat pump devices (20a1, 20a2,..., 20a(n-1)) other than the most downstream heat pump device such that the variation amount to be allocated to the most downstream heat pump device is smaller than the variation amount at the normal time, at a predetermined timing; and characterized in that the variation amount allocation determining unit is configured to determine the variation amount to be allocated to the plurality of heat pump devices (20a1, 20a2,..., 20a(n-1)) other than the most downstream heat pump device such that the variation amount to be allocated to the most downstream heat pump device at a predetermined timing is smaller than the variation amount at the normal time when the variation amount allocation determining unit determines that a target temperature of the water at output of the most downstream heat pump device exceeds a first set temperature.