provided are corrosive environment monitoring systems and methods whereby corrosive factors are measured in a steam turbine and a corrosive environment is correctly monitored . more specifically , provided is a corrosive environment monitoring system which measures corrosive factors having a part in damaging and deteriorating structural members in a steam turbine and which is configured in such a way that steam in the steam turbine is permitted to flow into the corrosive environment monitoring system . furthermore , in the steam turbine , there are provided a condensing mechanism which condenses steam that has flowed in and a corrosive factor measuring device which is equipped with corrosive factor sensors that measure corrosive factors in condensed water generated by the condensing mechanism .