To provide a turbine installation and a turbine generator capable of realizing higher energy efficiency and output.

This turbine installation comprises a turbine which exhausts expanded gas from a turbine outlet; a decompression apparatus which sucks the gas from a decompression apparatus inlet and forcibly exhaust it to a decompression apparatus outlet; and a steam turbine which sucks steam from steam turbine inlet. The turbine outlet is communicated with the decompression apparatus inlet, and the steam turbine drives the decompression apparatus.