To obtain an enterokinesis inhibitor which has an inhibitory action on peristalsis of the stomach, does not cause a clinical adverse effect with high safety, is effective for treatment before digestive tract examination, gastrointestinal X-ray examination, abdominal MRI examination, endoscopy, etc., can be provided as a solution, thus simply used and is economic.

This peptide comprises and amino acid sequence from N terminal to at least 23rd amino acid sequence of an amino acid sequence represented by formula (I) His-Xal-Asp-Xa2-Xa3-Phe-Thr-Xa4-Xa5-Xa6-Xa7-Leu-Leu-Xa8-Xa9- Leu-Xa10-Xa11-Xa12-Lys-Tyr-Leu-Xa13-Ser-Xa14-Xa15-Gly-Ser-Xa16-Thr-Ser-Pro- Xa17-Pro-Pro-Ser-Ser (I) (Xa1 to Xa17 can take 2 or 3 specific amino acids, respectively) and has an inhibitory action of enterokinesis. This enterokinesis inhibitor comprises the peptide or its pharmacologically acceptable salt as an active ingredient.