Abstract: The present invention relates to a peptide derivative represented by the general formula (I) or a salt thereof: Z-(CH2)n—CO—NH-Leu-Ile-Gly-AA1-AA2-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: AA1-AA2 represents Lys-Val or Arg-Leu; and R represents —OH or —NH2, 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.