A 1,3,5-triazine derivative represented by the following formula (I) ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4, independently from each other, represent a hydrogen atom or a group selected from the class consisting of linear or branched C.sub.1 -C.sub.6 alkyl groups, C.sub.2 -C.sub.6 alkenyl groups, C.sub.2 -C.sub.6 alkynyl groups, C.sub.1 -C.sub.6 alkyl groups substituted by C.sub.1 -C.sub.6 alkoxy or alkylthio, C.sub.3 -C.sub.6 cycloalkyl groups, a phenyl group unsubstituted or substituted by a substituent selected from halogen, nitro, cyano, lower alkyl, lower alkoxy, lower alkylthio and fluoro-substituted lower alkyl, C.sub.7 -C.sub.9 aralkyl groups unsubstituted or substituted by a substituent selected from halogen, nitro, cyano, lower alkyl, lower alkoxy, lower alkylthio and fluoro-substituted lower alkyl, and alkoxycarbonylmethyl groups having 1 to 6 carbon atoms in the alkoxy moiety; and Y represents a fluoro-substituted C.sub.1 -C.sub.3 alkyl group and a herbicidal use thereof.