This invention relates to a novel N-acyl acidic amino acid diamide derivative represented by the general formula or a salt thereof: ##STR1## wherein each of R.sup.1, R.sup.2, R.sup.3 and R.sup.4, which may be the same or different, represents a hydrogen atom or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl or aralkyl group, or R.sup.1 and R.sup.2 and/or R.sup.3 and R.sup.4, when taken together with the respective adjacent nitrogen atoms, form a substituted or unsubstituted heterocyclic group; R.sup.5 represents a substituted or unsubstituted cycloalkyl, acyl or heterocyclic group; A represents a bond or a substituted or unsubstituted alkylene, alkenylene or alkadienylene group; and n is 1, 2 or 3. Said compound has an anti-ulcer activity which is effective to human beings and animals. This disclosure relates to such a compound, to a process for the production thereof and to an anti-ulcer agent containing the same.