The object of the present invention is to provide a material with a low environmental load, which is a preparation that inhibits and/or removes the formation of biofilms, not only can be dispersed in water, but also continues to be effective even in an environment such as a water area, and thus has high safety . The present invention is a water-dispersible microparticle, which contains a complex composed of a polycarboxylic acid derivative and a drug.本發明之課題在於提供一種低環境負荷的材料，係作為抑制及／或去除生物膜的形成之製劑，不僅可分散於水，而且即使在用水區等之環境下效果仍持續，進而安全性高。本發明為一種水分散性之微粒子，係包含由聚羧酸衍生物與藥劑所構成之複合體。
