A ６２-year-old man was seen for repeated cholangitis. After further examination, he was performed an operation under the diagnosis of mucin producing bile duct tumor in left hepatic lobe. There was no evidence of malignancy, but we performed a left hepatic lobectomy with lymph node dissection, because mucin producing bile duct tumors reported tend to be malignant. On pathology, a diagnosis of intraductal papillary neoplasm of the bile duct（IPNB）was made. IPNB is equivalent to IPMN in the biliary tract, and more and more IPNB cases have been reported. We are not certain of all of the differences between IPNBs and known diseases（e.g., mucin producing bile duct tumors）. Although not all cases of IPMN are indicated for operation, we should consider resection in every case of IPNB regardless of its malignant potential, because it can cause severe complications（e.g., cholangitis and jaundice）. Our case underscores the need for suspection of IPNB in cases of repeated cholangitis
