A hot water supply system includes a hot water supply apparatus, a plurality of supply paths, and an estimation unit. The hot water supply apparatus includes a heating apparatus configured to heat water, a tank configured to store the water heated by the heating apparatus, and a water circuit configured to circulate the water in the tank. Each supply path is coupled to a corresponding one of a plurality of hot water supply targets and is configured to supply the water from the tank. The estimation unit is configured to predict a total amount of hot water supply demand, based on time-series data of a first index that indicates an amount of heat of water used in each of the plurality of hot water supply targets.