Provided is a method for producing a fuel cell separator which can achieve a stable power generation over a prolonged period of time and a method of producing the fuel cell separator. The fuel cell separator has a recess for gas flow path whose surface is roughened in such a manner that the arithmetic mean roughness Ra is 0.5 to 10 μm, and the recess for gas flow path is brought into contact with a fluorine-containing gas or a gas containing both fluorine and oxygen. The thus obtained fuel cell separator can retain a uniform liquid film formed on the surface thereof for at least 10 seconds when a test piece prepared from the fuel cell separator is immersed in water for 30 seconds and pulled out therefrom to a position at not less than 1 cm from the water surface within 1 second.