A solid state and conductive polymer composition comprising a host copolymer shown in the general formula: ##STR1## wherein n is an integer in the range of 3 to 1.times.10.sup.-7, m is an integer in the range of 3 to 100, R is --C.sub.6 H.sub.3 (CH.sub.3)-- or --(CH.sub.2).sub.l -- (l is an integer in the range of 1 to 10), A is hydrogen atom or side chain and the mole fraction of PEO units in the host copolymer is not less than 5% and a supporting electrolyte containing at least one of salts consisting of alkali metal salt, alkaline earth metal salt, ammonium salt, transition matal salt and a solid acid, a supporting electrolyte being admixed in an amount in the range of 0.1 to 400 parts by weight per 100 parts by weight of the host copolymer.