The invention intends to provide a bioassay method using a simple in-vitro test for Daikinchuto, and further to provide a more highly accurate method for quality control of Daikenchuto using the same. These methods are a bioassay method for the pharmacological activity of Daikenchuto, characterized in that a test sample containing Daikenchuto is added to cultured serotonin-producing cells, and the serotonin content in the culture supernatant is subsequently measured; and a quality control method for Daikenchuto preparations in which the pharmacological activity of a test preparation and a reference preparation for which the pharmacological effect as Daikenchuto has been clinically confirmed are evaluated under the same conditions, and the equivalence of the reference preparation and testing preparation is evaluated.