The steam generating device includes temperature increasing unit that turns water into steam, heat source that supplies heat to temperature increasing unit, and water storage unit that has a recess below temperature increasing unit. Temperature increasing unit of steam generating device is preheated to a predetermined temperature, and water stored in water storage unit contacts with temperature increasing unit. According to this configuration, a large volume of steam can be instantaneously generated, and scale adhesion can be reduced because a scale component dissolves in the water in water storage unit.