The present invention aims to provide a peptide having a superior Y2 receptor agonist action and useful as an agent for the prophylaxis or treatment of obesity and the like.A peptide represented by the formula: P1-X1-A25-A26-A27-A28-A29-A30-A31-A32-A33-A34-A35-A36-NH2wherein each symbol is as described in the specification, or a salt thereof.