Primary enteroliths associated with Crohn's disease have been considered to be rare and are most likely caused by severe ileal stenosis. Herein, we report the case of a primary enterolith possibly caused by mild jejunal stenosis in a Crohn's disease patient who received oral administration of ursodeoxycholic acid (UDCA). A 62-year-old woman with a 6-year history of Crohn's disease, currently in clinical remission, was on UDCA prescription for liver dysfunction. Magnetic resonance imaging and double-balloon endoscopy, which were performed to examine epigastric pain, revealed mild jejunal stenosis and an enterolith on the oral side. Since it was difficult to remove or crush the enterolith endoscopically, we decided to remove it surgically with the stenotic jejunum. Component analysis revealed that more than 98% of the enterolith was composed of UDCA; subsequently, oral administration of UDCA was discontinued. This case demonstrated that primary enterolith might develop in Crohn's disease patients with mild intestinal stenosis, and oral administration of UDCA can trigger an enterolith in such patients. Therefore, routine follow-up imaging is necessary for early detection. Oral UDCA should be administered with caution for Crohn's disease patients with stenosis of the proximal small intestine.