Image forming method comprising a step of fixing a toner image in a fixing device of a contact heating system, wherein the toner comprises a resin which comprises a polyester resin and a styrene-aryl resin and is formed by a process comprising allowing a polyvalent carboxylic acid and a polyvalent alcohol to condensation-polymerize in the presence of a styrene monomer and an acrylic acid ester monomer in an aqueous medium to form the polyester resin and allowing the styrene monomer and the acrylic acid ester monomer to radical-polymerize to form the styrene-acryl resin; the fixing device of a contact heating system comprises a heating roller and a belt-form pressure means.