A compound represented by the following Formula (I) or a salt thereof, as well as a formulation for controlling harmful organisms, and in particular, an insecticidal formulation, a miticidal formulation, a formulation for controlling ectoparasites or a formulation for controlling or killing endoparasites, which contains at least one compound selected from the compounds of Formula (I) and salts thereof as an active ingredient wherein, each of R1 and R2 independently represents a hydrogen atom, a substituted or unsubstituted C1-6 alkyl group, or the like, with the proviso that when R2 represents a hydrogen atom, R1 represents a substituted or unsubstituted C6-10 aryl group or a substituted or unsubstituted 3- to 6-membered heterocyclyl group; R3 represents a C1-6 alkylthio group or the like; each of R4 and R5 independently represents a hydrogen atom, a halogeno group or the like; and Ar represents a substituted or unsubstituted C6-10 aryl group, or a substituted or unsubstituted 5- to 6-membered heteroaryl group.