A 38-year-old woman was referred to our institution due to epigastralgia. She presented with obstructive jaundice and eosinophilia. Endoscopic retrograde cholangiopancreatography showed diffuse narrowing from the distal common bile duct to the bifurcation of the hepatic ducts. An endoscopic plastic biliary stent was inserted; the specimen obtained from the common bile duct wall revealed dense infiltration by eosinophils.Treatment was started with prednisolone 60 mg daily.The patient's biliary stenosis and eosinophilia gradually improved. Eosinophilic infiltration in the lungs or stomach is relatively common, but it is rare in the common bile dud. Most of the reported cases of eosinophilic cholangitis presented with eosinophilia; our patient's eosinophil count was over 1000/mm3. Since our patient had allergies to pollen and house dust, a relationship between the allergies and the eosinophilic cholangitis was suspected, but no cause was identified.