To provide a hot water supply device which shortens waiting time until hot water heated by a heat exchanger appears after starting hot water supply operation.

This hot water supply device has: the water heating heat exchanger 2 connected with a water entering passage 5 for supplying hot and cold water and a hot water discharge passage 6 for allowing the heated hot and cold water to appear; a burner 3 for heating this heat exchanger 2; a fuel supply quantity adjusting means N for changing and adjusting a fuel supply quantity to this burner 3; a fan 4 for ventilating combustion air to the burner 3; a rotating speed detecting means 9 for detecting a rotating speed of this fan 4; and an ignition means 14 for performing ignition operation to the burner 3. When commanding ignition, after starting the fan 4, when becoming ignition starting time until the rotating speed of the fan 4 increases to a target rotating speed for ignition, the ignition operation to the burner 3 is started, and the fuel supply quantity to the burner 3 is controlled so as to gradually increase toward a target fuel supply quantity for the ignition.