Disclosed is a harmful organism control composition having a stable and high harmful organism control effect. The harmful organism control composition comprises: a pyridine compound represented by formula (I) or a salt thereof； and at least one efficacy-enhancing component selected from the group consisting of a nonionic surfactant, an anionic surfactant, a cationic surfactant, an ampholytic surfactant, an animal or plant oil, a mineral oil, a water-soluble polymer, a resin and a wax. [In formula (I), R
