To provide a novel peptide compound having high GLP-1 receptor/GIP receptor co-agonist activity and useful as an agent for the prophylaxis or treatment of obesity and the like.SOLUTION: The present invention provides H-Tyr-Aib-Glu-Gly-Thr-α-MePhe-Thr-Ser-Asp-Tyr-Aib-Lys-Tyr-Leu-Asp-Lys-Gln-Ala-Gln-Ala-Glu-Phe-Val-Lys-Trp-Leu-Leu-Lys-Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser-Lys-NHor salt thereof.SELECTED DRAWING: None