To provide an ice thermal accumulating system equipped with a water- cooled chiller which eliminates any extra works such as the replacing works for the water with brine or installation of excessive equipment such as a brine tank, etc., and also establishes a heating operation while deterioration of COP is precluded.

The ice thermal accumulating system 1 is configured so that an ice thermal accumulating chamber 4a, a heat-exchanger 4b to make heat exchange between the water and brine, and a brine pump 4d are installed in the sequence as named on a brine circulating passage 4 furnished with a water- cooled chiller 2 and leading from the brine outlet of an evaporator 2e constituting the chiller 2 to the brine inlet and is furnished with a heating load 6 in which a hot water having undergone a heat exchange by a condenser 2c constituting the chiller 2 circulates and a cooling load 5 in which a cold water having undergone a heat exchange by the heat exchanger 4b circulates, wherein an electric heater 4c to heat the brine flowing through the brine circulating passage 4 is interposed between the heat-exchanger 4b of the brine circulating passage 4 and the evaporator 2e.