A production method of controlled release particles 1 includes an oil phase component preparation step in which an oil phase component containing a hydrophobic slurry is prepared by dispersing, in a hydrophobic polymerizable vinyl monomer, an antibiotic compound that is hydrophobic and is substantially insoluble to the hydrophobic polymerizable vinyl monomer without the presence of a solvent a water dispersion step in which a hydrophobic slurry is dispersed in water to prepare an aqueous dispersion and a polymerization step in which the polymerizable vinyl monomer is subjected to suspension polymerization to produce a polymer.
