The method for producing a developing agent according to the invention contains subjecting the toner material dispersion liquid to mechanical shearing to make the granular mixture into fine particles, thereby providing a dispersion liquid containing fine particles having a smaller particle diameter than a particle diameter of the granular mixture. The toner material dispersion liquid is subjected to mechanical shearing under a temperature of a glass transition point Tg of the binder resin or more and a pressure of 10 MPa or more, and the resulting dispersion liquid containing the fine particles is depressurized with two or more stages while maintaining the temperature of a glass transition point Tg of the binder resin or more and then cooled to a temperature of a glass transition point Tg of the binder resin or less.