PURPOSE: To obtain a conductive polypyrrole having stable quality by polymerizing pyrrole through oxidation in a solution of an oxidizing agent/dopant obtained from a basic metal carboxylate and a sulfonic acid.

CONSTITUTION: A basic metal carboxylate selected among basic ferric, cupric and cerium carboxylates such as basic iron acetate represented by the formula: [Fe3O(O2CCH3)6(H2O)3]+CH3COO- is reacted with a stoichiometric amount (say, 3 equivalents per Fe atom) of an alkyl or arylsulfonic acid (e.g. 2,4,5- trichlorobenzenesulfonic acid) at 40°C or below in a solvent such as methanol to prepare a solution of an oxidizing agent/dopant of the basic metal sulfonate. Pyrrole is added to this solution and polymerized through oxidation to obtain a conductive polypyrrole precipitate, and the oxidizing agent/dopant reagent is recovered.