To solve a problem concerning an outer air intake filter unit for purifying air sucked into a gas turbine, wherein removal of alkaline gases or acidic gases contained in air, solid particles with the gases, and corrosible contaminated gas are required adding to removal of conventional dust particles in the air in an air intake opening of the gas turbine of a power generator facility along with environmental change in recent years.

In the intake filter unit for the gas turbine constituted by combining a plurality kinds of filters in a filter securing frame of an air intake opening of a gas turbine air intake unit, at least one kind of filter is a functional filter exhibiting highly effective dust collecting function even in low pressure loss using ultrathin fibers or a functional filter having highly effective dust collecting function even in low pressure loss and exhibiting an adsorbing function of the contaminated gas, and other kinds of filters are filters having dust collecting functions with different collecting ratios.