A method for producing a polylactic acid resin composition, including the following steps (1) and (2): step (1): subjecting an organic crystal nucleating agent to a wet pulverization in the presence of a carboxylic acid ester having a weight-average molecular weight of from 150 to 600 and a viscosity at 23° C. of from 1 to 500 mPa·s and/or a phosphoric ester having a weight-average molecular weight of from 150 to 600 and a viscosity at 23° C. of from 1 to 500 mPa·s to give a finely pulverized organic crystal nucleating agent composition; and step (2): melt-kneading a raw material for a polylactic acid resin composition comprising the finely pulverized organic crystal nucleating agent composition obtained in the step (1) and a polylactic acid resin.