NOVELTY - The separator has low ion dissolubility electroconductive substance embedded at the surface of stainless steel, titanium or titanium alloy. The arithmetic mean deviation of separator surface is 300microns or less. The point irregularity height of separator is 3-20microns. The value of curvature rate and twist rate of separator defined by predetermined formulas comprising parameters of length of line segments and maximum distortion height of separator with respect to longitudinal plane, is 0.1 or less. The contact resistance value of carbon paper is 15mOmegacm2 in 0.1Mpa of bearings.    USE - For fuel cell such as polymer electrolyte fuel cell, alkaline fuel cell, phosphoric acid type fuel cell, molten carbonate type fuel cell and solid oxide fuel cell used in electric vehicle and mobile personal computer.    ADVANTAGE - The flat property of separator is increased and high efficient separator is manufactured with low cost.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) separator manufacturing method involves coating carbide particle containing low ion dissolubility electroconductive substance having average particle diameter of 20microns or less, around carbide core material with average diameter of less than 200microns. The low ion dissolubility electroconductivity substance is embedded and electrically processed by mounting and projecting on air flow of pressure of 0.4Mpa or less. The collision energy of coating carbide particle is distributed by arranging a grid network eye jig and projecting the coated carbide particle between stainless steel, titanium, titanium alloy and carbide particle jet nozzle. The internal stress balance of separator is controlled by performing projection by roll diffusion bonding or press forming technique after molding stainless steel, titanium or titanium alloy; and    (2) method for evaluating curvature and twist of separator.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram illustrating method for evaluating flat property of separator of polymer electrolyte fuel cell.