PROBLEM TO BE SOLVED: To provide a biliary tract endoscope system in which a second insertion part of a cholangioscope is easily inserted into a papilla and which has a configuration to easily observe the inside of a pancreaticobiliary duct by the second insertion part after the insertion.SOLUTION: A biliary tract endoscope system includes: a side view type endoscope 101 having a first insertion part 102, and provided with a channel 110 and a cholangioscope 1 which can be inserted/extracted into/from the channel 110 and has a second insertion part 2 projected from an opening 110k after being inserted into the channel 110. The tip side of the second insertion part 2 is provided with a second curved part 12 bendable in a plurality of directions an active curve angle accompanying curve operation in the second curved part 12 is set to be 0-90° and a maximum curve angle at which the second curved part 12 is passively curved according to the impartment of external force is set to be 180-210°.
