A chilled water system comprising: a hot water supply system for generating hot water by waste heat from an engine, wherein a hot water heat exchanger performing heat exchange with a thermal fluid flowing through a waste heat recovery system connected to a waste heat system of the engine and a steam heat exchanger through which steam for heating supplied from an exhaust gas economizer or an auxiliary boiler is introduced are installed; an absorption chiller unit for generating chilled water at a predetermined temperature by performing heat exchange with the hot water generated by the hot water supply system; and a hot water temperature control system for adjusting a supply hot water flow on the basis of a temperature of the supply hot water so that a temperature of the supply hot water supplied from the hot water supply system to the absorption chiller unit becomes constant, the chilled water system further comprising: a flow meter for measuring the hot water flow; a thermometer for measuring a temperature of circulating hot water; and a circulation pump provided in the hot water supply system and configured to adjust a hot water flow rate, wherein if a temperature of the supply hot water lowers to the predetermined constant temperature or less, a speed of the circulation pump is controlled to be lowered, thereby reducing the waste heat amount absorbed in the absorption chiller unit, and if a temperature of the supply hot water rises to the predetermined constant temperature or more, a speed of the circulation pump is controlled to be increased, thereby increasing the waste heat amount absorbed in the absorption chiller unit. a hot water supply system for generating hot water by waste heat from an engine, wherein a hot water heat exchanger performing heat exchange with a thermal fluid flowing through a waste heat recovery system connected to a waste heat system of the engine and a steam heat exchanger through which steam for heating supplied from an exhaust gas economizer or an auxiliary boiler is introduced are installed; an absorption chiller unit for generating chilled water at a predetermined temperature by performing heat exchange with the hot water generated by the hot water supply system; and a hot water temperature control system for adjusting a supply hot water flow on the basis of a temperature of the supply hot water so that a temperature of the supply hot water supplied from the hot water supply system to the absorption chiller unit becomes constant, the chilled water system further comprising: a flow meter for measuring the hot water flow; a thermometer for measuring a temperature of circulating hot water; and a circulation pump provided in the hot water supply system and configured to adjust a hot water flow rate, wherein if a temperature of the supply hot water lowers to the predetermined constant temperature or less, a speed of the circulation pump is controlled to be lowered, thereby reducing the waste heat amount absorbed in the absorption chiller unit, and if a temperature of the supply hot water rises to the predetermined constant temperature or more, a speed of the circulation pump is controlled to be increased, thereby increasing the waste heat amount absorbed in the absorption chiller unit. a flow meter for measuring the hot water flow; a thermometer for measuring a temperature of circulating hot water; and a circulation pump provided in the hot water supply system and configured to adjust a hot water flow rate, wherein if a temperature of the supply hot water lowers to the predetermined constant temperature or less, a speed of the circulation pump is controlled to be lowered, thereby reducing the waste heat amount absorbed in the absorption chiller unit, and if a temperature of the supply hot water rises to the predetermined constant temperature or more, a speed of the circulation pump is controlled to be increased, thereby increasing the waste heat amount absorbed in the absorption chiller unit.