The present invention addresses the first problem of providing a novel technique for forming hyaluronan into particles. The present invention also addresses the second problem of providing a novel technique suited to the production of composite particles including an anionic polymer and a peptide. The means for solving the first problem is composite particles including an anionic polymer and a cationic polymer (excluding chitosan) having a degree of cationization of 0.2 or higher. The means for solving the second problem is to mix an anionic polymer and a peptide in an aqueous solvent having a pH of 5 or lower.