NOVELTY - A solid polymer electrolyte contains high molecular compound and electrolyte salt. The high molecular compound contains heat and/or actinic light polymerizable compound having poly or oligo carbonate group (1) or polymerizable functional group (2).    USE - For battery such as lithium cell and electric double layer capacitor (both claimed), especially as power supply for portable machines and backup power supply, for motor vehicles, large sized power supply for road leveling, as paper battery and for identity cards.    ADVANTAGE - The solid polymer electrolyte forms film with favorable strength and excellent ionic conductivity. The polymer electrolyte enables to manufacture battery and double layer capacitor of reduced thickness and having excellent workability over a long period of time, excellent heavy current characteristic and high temperature durability, reliability and stability.    DETAILED DESCRIPTION - A solid polymer electrolyte contains high molecular compound and electrolyte salt. The high molecular compound contains heat and/or actinic light polymerizable compound having poly or oligo carbonate group of formula (1) or polymerizable functional group of formula (2). The functional group of formula (2) is not of formula (3).    R1,R4=1-10C optionally branched and/or cyclic bivalent group containing hetero atom;    m=3-10;    n=2-1000;    R2,R3=H or 1-6C alkyl group;and    x=0 or 1-10.    INDEPENDENT CLAIMS are included for the following:    (i) battery which comprises the solid polymer electrolyte;    (ii) electric double layer capacitor which has polarizing electrode and the polymer electrolyte as ionic conductive substance;    (iii) manufacture of the solid polymer electrolyte which involves arranging polymerizable composition containing heat and/or actinic light polymerizable compound and electrolyte salt or organic solvent and/or inorganic oxide, on a support, and polymerizing the composition;    (iv) manufacture of the battery which involves arranging the polymerizable composition in a battery structure or a support and polymerizing the composition;    (v) manufacture of electric double layer capacitor which involves arranging the polymerizable composition in a double layer capacitor structure or a support and polymerizing the composition; and    (vi) polymerizable compound of formula (4).    R1,R2,m,n=same as defined above;and    R5=1-20C optionally branched and/or cyclic organic group containing hetero atom.