To provide a regenerative clean steam generating method and device by which clean dry steam can be generated according to load fluctuation even when the fluctuation is relatively large.

High-temperature high-pressure clean water 5 is led out from a clean steam generating pressure vessel 3 containing the water 5 through a pipe 23 connected to the bottom of the vessel 3 and again led into the water 5 contained in the vessel 3 as steam by heating the water 5 with the steam from a boiler 2 in heating equipment 1. The heat radiated from the steam is stored in the clean water 5 in the vessel 3 by assimilating the steam with the water 5 until the steam reaches at least the surface level of the water 5 so that the water 5 statically re-evaporates from the surface according to a load even when the load fluctuates. The clean dry steam thus obtained is led out from a vapor phase section 6 in the vessel 3.