NOVELTY - A gel solid electrolyte comprises a polysaccharide group polymer-inorganic polymer hybrid, a compound which dissolves an ion electroconductive metallic salt, and the ion electroconductive metallic salt.    USE - For gel solid electrolyte sheet, used for solid polymer electrolyte battery (both claimed). The solid polymer electrolyte battery is useful as power supply for machines such as notebook personal computers, mobile telephones, cordless phones, electronic notebooks, calculators, televisions e.g. liquid crystal televisions, electric shavers, power tools, electronic translating machines, audio input devices, memory cards, backup power supply, radio, headphone stereo cassette tape recorders, refrigerators, air conditioners, water heaters, microwave oven, dishwashers, washing machine, game machine devices, lighting equipment devices, toys, medical equipments, motor vehicles, electrically driven carts, electric power storage systems, and for navigation systems.    ADVANTAGE - The gel solid electrolyte has good film forming property, high ion electric conductivity, and excellent liquid retainability. The gel solid electrolyte sheet has high strength. A thin and compact solid polymer electrolyte battery is provided.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) gel solid electrolyte sheet, which is obtained by molding the gel solid electrolyte into sheet form;    (2) manufacture of the gel solid electrolyte sheet, which involves adding a catalyst to a solution of the polysaccharide group polymer and a metal alkoxide, and obtaining polymeric hybrid solution by hydrolyzing and polycondensing metal alkoxide. The obtained polymeric hybrid solution is applied on a carrier to form polymeric hybrid sheet. The obtained sheet is impregnated with a solution of ion electroconductive metallic salt; and    (3) solid polymer electrolyte battery, which has a positive electrode, a negative electrode, and a solid polymer electrolyte layer. The solid polymer electrolyte layer is equipped with the gel solid electrolyte sheet.