Azapeptide derivative

Disclosed is an azapeptide derivative represented by the formula (I): wherein A represents a direct bond, an alpha -amino acid or a residue of a dipeptide; R represents a hydrogen atom or a protective group for a terminal amino group; R represents a phenyl group or a phenyl group substituted by one or two substituents selected from the group consisting of a lower alkyl group, halogen atom, hydroxyl group which may be protected, nitro group, amino group which may be protected and perhalo lower alkyl group; and R represents a hydroxyl group or a protective group for a terminal carboxyl group, and a salt thereof, and an agent for curing nervous inflammation of respiratory apparatus, asthma and bronchospasm comprising the azapeptide derivative represented by the formula (I) or a salt thereof as an active ingredient.