PURPOSE: To improve conductivity and stability by incorporating a dope into a specific polymer containing silicon-nitrogen bonds.

CONSTITUTION: A dope containing ions of at least one member selected from among iodine, fluorine, bromine, and arsenic is incorporated in an amount of 0.5-20mol% into a polymer having a backbone which is represented by formula I or II (wherein R1 to R8 each is a 1-8C alkyl or phenyl) and contains Si-N bonds wherein the N atoms each has a double bond and the Si atoms each has single bonds only.