To provide a hot water supply device capable of reliably supplying hot water at a temperature over 100°C.

The hot water supply device 1 supplies hot water outside after heating the supplied water. The hot water supply device comprises a boiler body 22 which has a water flow-in part and a water flow-out part 22b and stores water, a water supply part 3 to supply water to the boiler body 22 via the water flow-in part 22a, an openable/closable hot water supply valve 25 to supply water in the boiler body 22 heated by the heater 23 outside via the water flow-out part 22b, a boiler hot water temperature sensor 24 to detect the temperature of water in the boiler body 22, and a hot water supply determination means to determine whether or not hot water at the temperature exceeding 100°C is supplied, and further comprises a control means which operates the heater 23, and opens the hot water supply valve 25 when the detected temperature of hot water in the boiler body 22 exceeds 100°C if it is determined that hot water at the temperature exceeding 100°C is supplied.