A toner manufacturing process capable of providing a toner with uniform charge amounts. A mixture of a synthetic resin having an acidic leaving group and a coloring agent as essential components is emulsified in an aqueous solution to produce synthetic resin particles containing the coloring agent. If desired, the resin particles are further aggregated to form aggregated resin particles. The synthetic resin particles are then separated, washed and dried. The washing of the toner particles is conducted using a washing water prepared by dissolving carbon dioxide in water with a conductivity of not more than 20 .mu.S/cm.