A method for manufacturing a developing agent includes forming a toner particle by adding an aggregating agent to a dispersion containing fine particles containing a binder resin and a colorant to allow aggregation and melt adhesion to occur, wherein the pH of the dispersion satisfies the formula (1) below, when denoting pH before the addition of the aggregating agent by pH(A), the pH of the dispersion after the addition of the aggregating agent by pH(B), and the pH of the dispersion after the melt adhesion by pH(C): 0.90.gtoreq.pH(C)/pH(A).gtoreq.0.25 and 1.00.gtoreq.pH(C)/pH(B).gtoreq.0.30 (1).