To provide a snow melting system using a heat storage tank for recovering exhaust heat from a factory or secondarily heating the same by a gas boiler, and utilizing hot water stored in the heat storage tank in melting snow on a roof.

This snow melting system using the heat storage tank is composed of the heat storage tank 1 of high heat retaining property, the gas boiler 2 for heating, compensating insufficient temperature, an exhaust heat recovering unit 3 for recovering the exhaust heat from the factory, a load heating device 4 for circulating heat energy from the heat storage tank to load heating, a daily life water utilizing device 5 for utilizing the hot water in the heat storage tank in washing a lavatory bowl in a toilet, washing a car and watering trees and flowers, a roof snow melting device 6 for utilizing the hot water or heat energy in the heat storage tank in melting the snow on the roof, and a hot water supply device 7 for supplying hot water to a bathtub, a shower and a washbowl.