PURPOSE: To obtain electric charge controlling resin particles easy to charge and strong in adherence between core particle and microparticle and superior in durability by adjusting pH value of suspension in the case of heat treating of core particle and microparticle.

CONSTITUTION: Switable core particles are those having positive electric charge in water family medium, desirably copolymer in respects of moisture resistance and electric charge control among monomers and the like having nitrogen atoms in a molecule, for instance, nitrogenous monomers, such as dimethylaminoacrylate, dimethylaminoethylacrylate, and the like. Moreover, usable microparticles are those having negative electric charge in the water family medium so as to be electrically stuck to this core particle, for instance, homopolymer of a monomer having sulfonic acid radical -SO3H in a molecule or copolymer with other monomers. In the case of suspension polymerization, if hard water soluble inorganic powder, for instance, calcium sulfate, or barium carbonate, and the like is used as a suspension stabilizer, the powder is melted in the water family medium by adjusting pH. When the core particles and the microparticles are fused together by heat treatment, they are never disturbed by the hard water soluble inorganic powder, but strong in fusion between the core particles and the microparticles.