To provide a water feeding device for a hot water storage tank controlling an amount of water to be supplied into the tank on the basis of a temperature of hot water stored in the hot water storage tank.

The water feeding device for the hot water storage tank is provided with a heating means for heating the hot water in the hot water storage tank, a temperature sensor arranged in an interior of the hot water storage tank for detecting the temperature of the hot water in the tank, and a feed valve provided in a feed water pipe, opened when the temperature sensor detects a preset lower limit set temperature to supply water into the hot water storage tank from the feed water pipe, and closed when the water temperature in the tank drops due to supply of the water and the temperature sensor does not detect the preset lower limit set temperature to interrupt the supply of water from the water feed pipe. When the water temperature is raised by heating of the heating means after closing of the feed valve, and the temperature sensor detects the lower limit set temperature, the feed valve is opened to resume the supply of the water.