A high-temperature steam turbine plant is of the top turbine type and structured as follows. It comprises a boiler building including a vertical boiler on the top of which a VHT turbine is installed; and a turbine building installed on the ground as a base. The VHT turbine and a generator connected with it are installed on the top of the boiler. The material for the portion of the steam pipe between the boiler building and the turbine building which is exposed to highest steam pressure is austenite steel which contains 50 weight % or more of ferrite steel or Fe. The inlet temperature of the VHT turbine is 675° C. or more and its outlet temperature is 550° C. or more and 650° C. or less.