A negative-chargeability control resin containing a specific vinyl copolymer imparts stable chargeability to toner. The vinyl copolymer is obtainable by copolymerizing a monomer composition which contains at least i) a vinyl monomer (A) as exemplified by N-acryloylmorpholine, N-isopropylacrylamide, N-methylmethacrylamide, N-butoxymethylacrylamide or N-t-butylacrylamide, or a vinyl monomer (B) as exemplified by vinyl butyrate, vinyl 2-ethylhexanoate, vinyl benzoate, vinyl monochloroacetate pivarate, and ii) a vinyl monomer (C) having as a functional group a carboxyl group or a carboxyl group made into salt structure.
Negative-chargeability control resin