To provide a hot water supply system capable of effectively activating natural energy.

This hot water supply system comprises a heating medium circulating circuit 4 having a heat capturing part 3 for absorbing ground heat, a heat pump 6 for absorbing the heat from the heating medium flowing in the circulating circuit 4, and a hot water storage tank 2 having a first heating coil 81 in which the heating medium heated by the heat pump 6 flows. A heat collector 5 is connected to the circulating circuit 4, and a second heating coil 82 connected to the circulating circuit 4 is mounted on the hot water storage tank 2. Further a flow channel switching means is mounted on the circulating circuit 4 for switching a state allowing the heating medium to flow to the heat collector and the second heating coil 82 without passing through the heat capturing part 3, a state for allowing the heating medium to flow to the heat collector 5 and the heat capturing part 3 without passing through the second heating coil, and a state for allowing the heating medium to flow to the heat capturing part 3 without passing through the heat collector 5 and the second heating coil 82. The operations of the flow channel switching means and the heat pump 6 are controlled on the basis of a temperature T1, a temperature T2 and a water temperature T3.