PROBLEM TO BE SOLVED: To provide an anti-biotic active particle having excellent appearance after long-term exposure and a method of producing the same.SOLUTION: Anti-biotic active particles are obtained by dispersing a hydrophobic solution containing monomer components and an anti-biotic active compound in water, and then polymerizing the monomer components of the hydrophobic solution dispersed in water, in the presence of inorganic particles having a high refractive index.