A method for producing a conductive polyaniline comprising oxidative polymerizing aniline or its derivative in the presence of at least one member of a sulfonic acid compound and a water-insoluble organic polymer compound having protonic acid group in a mixed layer composed of an aqueous layer and organic layer, during which it establishes the presence of a molecular weight adjusting agent and, optionally, a phase transfer catalyst so as to stably disperse them in an organic solvent, and an organic polymer composition containing the conductive polyaniline.