PURPOSE: To prevent corrosion and the like in a steam generating device for a steam plant, which is generated by introducing impurities, such as iron series and the like which are removed from wet steam from a turbine and contained in drain.

CONSTITUTION: Moisture in the wet steam of a high pressure turbine 2, driven by steam generated in a steam generating device 1, is removed by a moisture separator 3 as drain 12 while the exhaust steam of a low pressure turbine driven by the steam, whose moisture is removed already, is condensed in a condenser 6 and said drain and condensed water are circulated into the steam generating device 1 for a steam plant. The steam plant comprises a feed water heater 10, recovering the heat of drain removed from steam into water circulated to said steam generating device 1 and supplying the drain into the condenser 6, and a desalting device 8, provided at the down-stream side of the condenser 6 and removing impurities in water.