A hot water supply system comprising: a tank including a hot water storage tank that stores hot water; a case that holds the tank; a plurality of pipes (20, 21, 22, 23) each including a connection portion (20a, 21a, 22a, 23a) connected to the tank and an extension portion (20b, 21b, 22b, 23b) bending from the connection portion (20a, 21a, 22a, 23a) and extending to an end portion of the tank; and a heat insulation member surrounding the tank, the plurality of pipes (20, 21, 22, 23) includes a water supply pipe for supplying water to the hot water storage tank, and a hot water discharge pipe, for discharging the water heated by a heat exchanger from the hot water storage tank, wherein the heat insulation member forms, between the tank and the heat insulation member, a space where the connection portion (20a, 21a, 22a, 23a) and at least a part of the extension portion (20b, 21b, 22b, 23b) of pipes (20, 21, 22, 23) are disposed, characterized in that the system comprises a case that holds the tank, wherein the heat insulation member surrounds the tank inside the case, the plurality of pipes (20, 21, 22, 23) each include the connection portion (20a, 21a, 22a, 23a) inside the case and the extension portion (20b, 21b, 22b, 23b) inside the case, in said space the connection portion (20a, 21a, 22a, 23a) and at least a part of the extension portion (20b, 21b, 22b, 23b) of every pipe except the water supply pipe are disposed, the extension portion of the water supply pipe for supplying water to the tank among the plurality of pipes (20, 21, 22, 23) is disposed outside this space, and the tank includes a heat exchanger connected to a fluid circuit (10a, 10b, 10c) in which there is a fluid for circulation, the heat exchanger for heating the water stored in the hot water storage tank using the fluid circulating in the fluid circuit, the plurality of pipes (20, 21, 22, 23) includes an inlet pipe for flowing the fluid circulating in the fluid circuit into the heat exchanger, and a return pipe for returning the fluid used by the heat exchanger to the fluid circuit. a tank including a hot water storage tank that stores hot water; a case that holds the tank; a plurality of pipes (20, 21, 22, 23) each including a connection portion (20a, 21a, 22a, 23a) connected to the tank and an extension portion (20b, 21b, 22b, 23b) bending from the connection portion (20a, 21a, 22a, 23a) and extending to an end portion of the tank; and a heat insulation member surrounding the tank, the plurality of pipes (20, 21, 22, 23) includes a water supply pipe for supplying water to the hot water storage tank, and a hot water discharge pipe, for discharging the water heated by a heat exchanger from the hot water storage tank, wherein the heat insulation member forms, between the tank and the heat insulation member, a space where the connection portion (20a, 21a, 22a, 23a) and at least a part of the extension portion (20b, 21b, 22b, 23b) of pipes (20, 21, 22, 23) are disposed, characterized in that the system comprises a case that holds the tank, wherein the heat insulation member surrounds the tank inside the case, the plurality of pipes (20, 21, 22, 23) each include the connection portion (20a, 21a, 22a, 23a) inside the case and the extension portion (20b, 21b, 22b, 23b) inside the case, in said space the connection portion (20a, 21a, 22a, 23a) and at least a part of the extension portion (20b, 21b, 22b, 23b) of every pipe except the water supply pipe are disposed, the extension portion of the water supply pipe for supplying water to the tank among the plurality of pipes (20, 21, 22, 23) is disposed outside this space, and the tank includes a heat exchanger connected to a fluid circuit (10a, 10b, 10c) in which there is a fluid for circulation, the heat exchanger for heating the water stored in the hot water storage tank using the fluid circulating in the fluid circuit, the plurality of pipes (20, 21, 22, 23) includes an inlet pipe for flowing the fluid circulating in the fluid circuit into the heat exchanger, and a return pipe for returning the fluid used by the heat exchanger to the fluid circuit.