The present invention intends to suppress energy consumption despite making it possible to generate superheated steam in a short period of time. Specifically, the present invention includes: a steam generating part 10 that generates steam; a superheated steam generating part 20 that generates superheated steam; and an on/off valve 40 that switches the supply of the steam to the superheated steam generating part 20 or the stop of the supply, wherein the on/off valve 40 switches the supply of the steam or the stop of the supply, and thereby switching is performed between a waiting state that is a state where the steam generating part 10 generates the steam and a state where the supply of the steam is stopped, and a supply state where the steam is supplied to the superheated steam generating part 20.
