To provide a method for stably producing a coated particulate bioactive substance having certain functions by solving the problem that in the production of the substance required to have many functions such as a controlled elution rate, an elution pattern, a temperature dependency, and the decomposability of the coating material used, among many types of coating material components used, part of a coating material component (minor component) used in a small amount scatters or adheres to the wall of a dissolution tank when it is dissolved in or mixed with a solvent, which leads to the dispersion or deficiency of the content of the minor component in the coat of the coated product.

The method is one for producing the coated particulate bioactive substance by using a coating material containing the minor component and a resin component, wherein the coating material is a resin component prepared by previously milling the minor component with the above resin component.