TECHNOLOGY FOCUS - POLYMERS - Preferred Electrolyte: Alternatively, the solid electrolyte is obtained by using as raw material components:(a) silane coupling agent having at least organic substituent, compound having phosphoric acid group and addition type polyimide resin;(b) silane coupling agent, compound having phosphoric acid group and compound having phenolic hydroxyl group;(c) epoxy resin and compound having phosphoric acid group;(d) epoxy resin, compound having phosphoric acid group and addition type polyimide resin; or(e) epoxy resin, compound having phosphoric acid group and compound having phenolic hydroxyl group,Preferred Compound: The compound having phenolic hydroxyl group is polyparavinyl phenol or phenol resin.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compounds: The compound having phosphoric acid group is Phosmer(RTM). EXAMPLE - 3,3',4,4'-Benzophenone tetracarboxylic acid dianhydride (in g) (161.1) and methanol (225.2) were mixed and heated to boiling point. The reaction was performed for 5 hours, and methanol solution of 3,3'-dimethoxy carboxy-4,4'-dicarboxybenzophenone (A) was obtained. 4,4'-diaminodiphenylmethane (1.09) and methanol (1.09) were dissolved at room temperature and mixed with solution (A) (3.86), and stirred for 10 minutes to form solution (B). The obtained solution (B) (3.5) was added to methanol (4.28), 3-glycidyloxy propyltrimethoxysilane (4.5) and tetramethoxysilane (2.86) and stirring was performed. Aqueous solution of orthophosphoric acid (6.51) was added to the mixture, and distilled water (1.05) was added and stirred for 10 minutes to obtain solution of polyimide monomer / 3-glycidyloxypropyltrimethoxysilane / tetramethoxysilane / phosphoric acid group compounds (C). The obtained solution (C) (3) was cast on a formwork of polypropylene, and air-drying was performed. The applied film was heated at 50degreesC for 24 hours and at 150degreesC for 5 hours. The obtained film was interposed with platinum foil, to obtain solid electrolyte film. The film had ionic conductivity of 1.2x10-3 S/cm at 60degreesC and 4.2% relative humidity.