Abstract: A controlled release particle includes a core containing an antibiotic compound, and a shell covering the core. The controlled release particle is obtained by a production method including a first step in which a first component containing an antibiotic compound and a polymerizable vinyl monomer is subjected to suspension polymerization to form the core containing the antibiotic compound and a polymer of the polymerizable vinyl monomer; and a second step in which a second component containing a shell-forming component is subjected to interfacial polymerization to form a shell, wherein in the second step, the interfacial polymerization is started simultaneously with the start of the suspension polymerization of the first step, or started after the start of the suspension polymerization of the first step.