Abstract: Disclosed is a water heater including a case provided with an air supply hole and an air discharge hole, a burner provided in an interior of the case, and a humidified air supply part that provides humidified air to the burner together with a fuel. The humidified air supply part includes a first accommodation tank that accommodates water to generate vapor, and a humidified air supply tank that provides a space for supplying the vapor supplied from the first accommodation tank to air introduced into an interior of the case through the air supply hole.