Producing a resin particle dispersion using an apparatus including: two or more resin particle dispersion production lines each including an emulsification tank in which a resin is subjected to phase inversion emulsification using two or more organic solvents and an aqueous medium to obtain a phase-inverted emulsion, a distillation tank in which the organic solvents are removed from the phase-inverted emulsion by reduced pressure distillation to obtain a resin particle dispersion, and plural distillate collection tanks that collect distillates formed during the reduced pressure distillation according to respective target distillate compositions; and a reusable storage tank that collects and stores a distillate collected in at least one collection tank among the distillates collected in the plural collection tanks in each of the two or more production lines, and delivering the distillate to the emulsification tank in at least one production line to reuse the distillate for producing a phase-inverted emulsion.