Patent ID: 8425407

Claim:
An endoscope insertion portion comprising: an image pick-up assembly extending in an axial direction in the endoscope insertion portion, and the image pick-up assembly including: an image pick-up unit and an image pick-up cable extending from a proximal end of the image pick-up unit to the proximal end of the insertion portion wherein an outer diameter of the image pick-up unit is larger than an outer diameter of the image pick-up cable; and a channel assembly extending in the axial direction in the endoscope insertion portion, arranged side by side with the image pick-up assembly, and including: a channel pipe which includes a thin outer diameter portion and a channel tube which includes a thick outer diameter portion including an outer diameter larger than an outer diameter of the thin outer diameter portion and which is provided to the proximal end of the channel pipe, wherein a distal end portion of the thick outer diameter portion of the channel tube is arranged on a more proximal end side than a proximal end portion of the image pick-up unit; and wherein the endoscope insertion portion includes a distal end forming portion and a bending portion provided in order from the distal end portion of the endoscope insertion portion to the proximal end portion of the endoscope insertion portion, the bending portion includes a plurality of cylindrical bending parts coupled to each other in the axial direction so as to be rotatable relative to each other and including a first bending part on the most distal end coaxially coupled to the distal end forming portion and a second bending part coupled to the proximal end side of the first bending part, and a central axis of the second bending part is arranged so as to be off-set from a side close to the image sick-us assembly to a side close to the channel assembly relative to a central axis of the first bending part in a cross-section orthogonal to the axial direction of the endoscope insertion portion.