The present invention provides a novel peptide compound having an activating action on GLP-1 receptors and GIP receptors and use of the peptide compound as a medicament. Specifically, a peptide containing a partial sequence represented by the formula (I) or a salt thereof and a medicament comprising the same are provided. P1-Tyr-Aib-Glu-Gly-Thr-alphaMePhe-Thr-Ser-Asp-Tyr-A11-A12-A13-Leu-Asp-A16-A17-Ala-Gln-A20-Glu-Phe-Val-Lys-Trp-Leu-Leu-Lys-A29 (I) wherein each symbol is as defined herein.