The present invention provides a method for operation for gas turbine power generation facility, the gas turbine power generation facility, comprising a compressor; a combustor; a gas turbine driven by combustion gases generated by the combustor; a generator having a rotor journal by water lubrication bearings; a cooling water circulating means for cooling the generator, wherein the cooling water is loaded into a cooling water box through a circulating water pump, and is fed to the generator by a radiator and then returned back to the cooling water box; a lubricating water supply device, constituted by the following form that a part of cooling water passing through the radiator of the cooling water circulating means feeds water to the water-lubricated bearing through a circulating water pump and the rest are loaded in a lubricating water tank at a position higher than the water-lubricated bearing, to feed water to the water-lubricated bearing from the lubricating water tank by utilizing potential energy, wherein the lubricating water from one or both of the circulating water pump and the lubricating water tank is supplied to the water-lubricated bearing during usual running, and the lubricating water is supplied from the lubricating water tank to when the circulating water pump is stopped due to malfunction.