TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Material: The carbonaceous material contains graphite and has average particle diameter of 3 nm to 50 microns. The graphite is particle-like graphite having average particle diameter of 3-12 microns, or particle-like graphite having average particle diameter of 3-12 microns and scale-like graphite having average particle diameter of 20-50 microns.    TECHNOLOGY FOCUS - POLYMERS - Preferred Resin: The polyimide resin is of formula (I).R1= tetravalent aromatic, tetravalent aliphatic or tetravalent organic group in which two aromatic groups are bonded to aliphatic group by single bond, -O-, -CO-, -SO2-, -CH2-, or -C(CF3)2-;R2= bivalent aromatic, bivalent aliphatic or bivalent organic group in which two aromatic groups are bonded to aliphatic group by single bond, -O-, -CO-, -SO2-, -CH2-, or -C(CF3)2-;andn=1 or more.Preferred Composition: The electroconductive paste composition further contains electroconductive powder containing metal and/or electroconductive oxide. Preferred Process: The electroconductive separator is obtained as follows. The metal separator base material formed in the defined shape, is roughened. Then, electroconductive paste composition is applied on the roughened surface of base material, and heat-hardened, to form electroconductive film. EXAMPLE - 2,2-bis(4-(4-amino phenoxy)phenyl)propane (in g) (36.9) was added to a flask into which bis((gamma)-aminopropyl)tetramethyl disiloxane (2.49) and N-methyl-2-pyrrolidone (279.1) were added. Then, 3,3',4,4'-biphenyl-ether tetracarboxylic-acid dianhydride (30.38) was added, stirred at room temperature for 12 hours in nitrogen atmosphere, to obtain polyamic-acid resin solution. The obtained polyamic-acid resin solution was re-precipitated using methanol to obtain polyamic-acid resin powder. The obtained polyamic-acid resin powder was dissolved using N-methyl-2-pyrrolidone and solid content was adjusted to 15%. The polyamic-acid resin powder (13.3 weight parts), SGL-3 (RTM: particle-like graphite) (2.7 weight parts) having particle size of 3 microns and SP-20 (RTM: scale-like graphite) (0.3 weight parts) having particle size of 20 microns were mixed. Then, terpineol was added and the viscosity of paste composition was adjusted, to obtain carbon type electroconductive paste composition. The obtained electroconductive-paste composition was applied on stainless steel plate and dried, to form electroconductive film. The obtained electroconductive film had volume resistivity of 0.09 ohms.cm based on JIS-K7194, strength of 9 H based on JIS-K5600, and excellent acid resistance based on JIS-K8001 and adhesivity based on JIS-K5600.