The present invention provides a novel method for producing fine particles of aripiprazole anhydride crystals B. The method for producing fine particles of aripiprazole anhydride crystals B comprises the steps of: (1) heating and dissolving crude aripiprazole in a lower alcohol, and subsequently cooling the resulting mixture to precipitate crystals to obtain crystals of aripiprazole lower alcohol solvate; (2) subjecting the crystals of aripiprazole lower alcohol solvate to wet-milling in the form of a slurry containing the lower alcohol; and (3) subjecting the dispersion of the wet-milled crystals to solid-liquid separation to obtain the crystals, and heating the crystals.