Abstract: 2-Aryl-4-isoxazolin-3-one derivatives having the following general formula (I): ##STR1## wherein R.sup.1 represents an alkyl group or an aryl group, R.sup.2, R.sup.3, and R.sup.4 each represents a hydrogen atom, a trifluoromethyl group, a carbamoyl group, a sulfamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group, a halogen atom, a cyano group, a nitro group, an alkoxy group, an aryloxy group, an acyl group, a carboxy group, or a sulfo group, with at least one of R.sup.2, R.sup.3, and R.sup.4 being selected from among a nitro group, a cyano group, a sulfamoyl group, a carbamoyl group, and a sulfonyl group, and X represents a monovalent group of one of a mercaptoazole, a mercaptoazaindene, a tetrazaindene, a mercaptopyrimidine a benzotriazole, an indazole, and a benzimiazole, are disclosed.