To provide water injection gas turbine facilities allowing the reduction of NOx without using a demineralizer requiring much installation cost and large installation space and increasing the size of a water treatment installation.

A gas turbine generator 12, a steam consumption installation 14 for consuming steam to generate condensate and a condensate injection line for injecting the condensate supplied from the steam consumption installation to a combustor 2 are provided so that supplied water is evaporated in an auxiliary boiler 16 and the condensate generated in the steam consumption installation is supplied to an exhaust heat boiler 13 and then injected to the combustor in a gas turbine.