The present invention relates to a peptide derivative represented by the general formula (I) or a salt thereof: Z-(CH.sub.2).sub.n--CO--NH-Leu-Ile-Gly-AA.sub.1-AA.sub.2-CO--R (I) wherein Z represents an aryl group which may or may not have a substituent or a heteroaryl group which may or may not have a substituent; n represents 0, 1 or 2: AA.sub.1-AA.sub.2 represents Lys-Val or Arg-Leu; and R represents --OH or --NH.sub.2, and relates to a pharmaceutical composition comprising a peptide derivative represented by the general formula (I) or a salt thereof, and a pharmaceutically acceptable carrier thereof. The peptide derivative is useful as a prophylactic and therapeutic agent of dysfunction of masticatory, dysphagia, dysgeusia, ozostomia, intra-oral cavity dysphoria, intra-oral cavity infections, intra-oral cavity inflammations, dry eye, ectocornea detachment, keratitis, corneal ulcer, conjunctivitis, stomach ulcer, duodenal ulcer, gastritis, diarrhea, enteritis or Sjogren's syndrome.