To provide a hot water storage type water heater capable of detecting residual quantity of high-temperature hot water in a hot water storage tank accurately.

A protection part 26 of a hot water storage temperature sensor 13 and a lead wire part 25 of a predetermined length from a boundary part between the protection part 26 and the lead wire part 25 are brought into contact with a hot water storage tank 1, and they are attached to the hot water storage tank 1 by being covered with an attaching member 27; thereby, the heat on the surface of the hot water storage tank 1 is transferred to the lead wire part 25, and the protection part 26 and the lead wire part 25 of the predetermined length from the boundary part between the protection part 26 and the lead wire part 25 become the same temperature as that on the surface of the hot water storage tank 1. Furthermore, the lead wire part 25 of the predetermined length from the boundary part between the protection part 26 and the lead wire part 25 is cut off from the surrounding outside air to prevent the influence of the outside air temperature. Thus, the temperature of the hot water in the hot water storage tank 1 can be detected accurately.