N-(.alpha.,.alpha.-dialkylbenzyl)-phenylacetamide compounds represented by the following general formula: ##STR1## wherein each of X.sub.1 and X.sub.2 is a halogen atom, an alkyl group containing from 1 to 3 carbon atoms, an alkoxyl group containing from 1 to 3 carbon atoms or a hydrogen atom; R.sub.1 is an alkoxyl group containing from 1 to 3 carbon atoms or a hydrogen atom; R.sub.2 is an alkyl group containing from 1 to 3 carbon atoms, and alkoxyalkyl group containing from 2 to 6 carbon atoms, an allyl group or a hydrogen atom; each of R.sub.3 and R.sub.4 is an alkyl group containing from 1 to 4 carbon atoms; and each of m and n is an integer of 1-3. This invention also provides herbicidal compositions comprising at least one of said compounds and a carrier.