An object of the present invention is to provide a process for producing stably a polymerized toner having excellent balance of shelf stability and fixability, and high resolution visible image formation. The process for producing a polymerized toner comprising a step of raising the temperature of an aqueous dispersion of monomer composition comprising a colorant, a polymerization initiator such as t-butyl peroxy-2-ethylhexanoate and a polymerizable monomer component such as styrene to a temperature lower than a target polymerization temperature by about 10 to about 40.degree. C., a step of raising the temperature of the dispersion at the rate of about 1 to about 20.degree. C. an hour to a temperature lower than the target polymerization temperature by about 5.degree. C., and a step of raising the temperature of the dispersion at the rate of about 3 to about 10.degree. C. an hour to the target polymerization temperature, whereby the polymerizable monomer component is polymerized.