[PROBLEMS] To provide a toner superior in shelf stability, not giving off an offensive odor and degrading the surrounding environment when used for printing, and superior in durability at the time of use for continuous printing under high temperature, high humidity conditions.[MEANS FOR SOLVING PROBLEMS] A process of production of a toner containing colored polymer particles obtained by polymerizing a polymerizable monomer composition containing a polymerizable monomer and colorant in an aqueous medium in the presence of a polymerization initiator, wherein the polymerization initiator is an organic peroxide having a molecular weight of 205 or less, and a purity of 90% or more.