Novel N'-phenyl-N-methylurea derivatives of the formula: ##STR1## wherein R.sub.1 is a hydrogen atom, a methyl group or a methoxy group, R.sub.2 is a hydrogen atom or a lower alkyl group, R.sub.3, which may be the same or different, is a halogen atom, a lower alkyl group, a lower alkoxy group, a lower alkylthio group or a trifluoromethyl group, n is an integer of 0 to 5, X is a hydrogen atom or a halogen atom, Y is an oxygen atom or a sulfur atom and Z is a straight or branched C.sub.1 -C.sub.8 alkylene group which may have no less than one atom of oxygen and/or sulfur at the terminal of and/or inside the carbon chain, which shows a pronounced herbicidal activity against a wide variety of weeds in the cultivation of crop plants as well as a notable fungicidal activity against a wide variety of phytopathogenic fungi causing plant diseases to crop plants without any material toxicity to mammals and fish or any chemical injury to said crop plants.