PURPOSE: To keep a specific composition high in ionic conductivity even at a room temperature and unmelted even at a temperature of 60°C and above, by forming the specific composition, out of a bridged resin for which a copolymerized polymer is bridged and out of a metallic salt.

CONSTITUTION: As an acryloil denaturation polyalkylene oxide, one of the components of a composition, triethylene glycol monoacrylate, or tetraethylene glycol monoacrylate, for example, are used, while the other component of the composition has a double bond in a molecule, and carboxyl group or hydroxyl group is used as a functional group, in an organic compound that has at least one functional group. These compositions are formed out of a bridged resin for which a copolymerized polymer is bridged and of a metallic salt. A high polymer solid electrolyte is thus obtained whose ionic conductivity is good even at a room temperature and which is not melted even at a temperature of 60°C and above.