Disclosed herein is a phenylhydrazone derivative of oxamide represented by the formula (I): ##STR1## wherein R.sup.1 is straight-chain alkyl group having 2 to 10 carbon atoms, branched alkyl group or cyclic alkyl group having 3 to 10 carbon atoms, alkyl group having 1 to 3 carbon atoms which is substituted with an alicyclic structure having 3 to 7 carbon atoms, phenyl group, halogen-substituted phenyl group, aralkyl group having 7 to 9 carbon atoms, alkenyl group having 3 to 6 carbon atoms, alkyl group having 2 to 4 carbon atoms which is substituted with alkoxy group having 1 to 4 carbon atoms, or alkyl group having 2 to 10 carbon atoms which is substituted with 1 to 19 fluorine atoms; and R.sup.2 is hydrogen, fluorine, chlorine, methyl group or methoxy group, and a herbicidal composition containing the derivative as active ingredient. The phenylhydrazone derivative of oxamide represented by the formula (I) of the present invention shows a high herbicidal activity and also have an excellent selectivity allowing killing of weeds alone without doing any practical harm to the crops such as rice, wheat and corn.