The invention provides an endoscope device, which enables a therapeutic device and an insertion part to be inserted in a thin tube cavity of a bravery pancreatic duct system easily without inserting in therapeutic device passing channel. The insertion part of the endoscope comprises a near-end insertion part comprising an approximately cylindrical outside surface and a distal end insertion part possessing a crescent cross section. A guide groove possessing the therapeutic device guiding the upper outer surface of the therapeutic device is formed in the distal end insertion part. At the same time, the near-end insertion part comprises therapeutic device passing channel equipped with a near-end opening at the therapeutic device guide groove. On the condition that the bending part of the distal end insertion part bends towards the therapeutic device guide groove side and is inserted in the cavity of the bravery pancreatic duct system, the therapeutic device is transmitted from the therapeutic device outlet, and then is guided into the cavity of the bravery pancreatic duct system via the therapeutic device guide groove.