Novel tetrahydrophthalamide derivatives of the general formula: ##STR1## wherein X is chlorine or bromine, and R is hydrogen, or an alkyl, a substituted alkyl, a cycloalkyl, a substituted cycloalkyl, an alkenyl, or an alkynyl group, have strong herbicidal activity and are particularly, useful for selectively controlling weeds without causing any substantial injury to soybean and other crop plants.