TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Film: A preferred film contains as the proton conductive substituent, a group selected from phenolic hydroxyl group, sulfonate group, carboxylate group and phosphate group. A preferred film contains a polyimide having a repeating structural unit (II).X1, X2 = same or different tetravalent organic groups;Y1 = divalent organic group having a proton conductive substituent;Y2 = divalent organic group having no proton conductive substituent;m = 1 or more;n = 0 or more.A preferred film contains a polyimide which is a reaction product between tetracarboxylic acid dianhydride and a diamine having no proton conductive subsistent and/or a polycondensation product of a diamine having no proton conductive substituent. SPECIFIC COMPOUNDS - The tetracarboxylic acid dianhydride is 1,4,5,8-naphthalene tetracarboxylic acid dianhydride. The diamine having proton conductive substituent is selected from 2,2'-benzidinesulfonic acid, 2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid and 3,3'-dimethyl-4,4'-diaminobiphenyl-6,6'-disulfonic acid. The diamine containing no proton conductive substituent is selected from 9,9-bis(4-aminophenyl)fluorine, 4,4'-diamino diphenyl ether, paraphenylene diamine and 2,2'-bis(4-(4-aminophenoxy)phenyl)propane. The polyfunctional component having three or more amino groups is 3,3'-diaminobenzidine.    EXAMPLE - 4.30 g of 2,2'-benzidinesulfonic acid, 105 g of phenol, 70 g of p-chlorophenol and 15.18 g of triethyl amine were added to a flask and stirred for 0.5 hours under nitrogen gas flow. 6.70 g of N-methyl-2-pyrrolidone, and 4.36 g of 9,9-bis(4-aminophenyl)fluorine were added in one portion then 50 g of toluene was added and stirred under nitrogen flow at 150 degreesC for 5 hours. The generating water was removed by azeotropy with toluene. The toluene was removed under reflux and the reactant was cooled to room temperature. 26.1 g of HCl and 1L of methanol were mixed vigorously and the reactant was added thereto dropwise and the resulting precipitate was washed with methanol, dried under reduced pressure at 120 degreesC for 3 hours to give the proton conductive polyimide resin composition.