Endoscope

An endoscope including an insertion portion including an observation optical system at a distal end portion disposed at a distal end thereof, a bending portion configured to bend in four directions that are a first direction, a second direction, a third direction and a fourth direction, the bending portion being provided so as to be continuous with a proximal end side of the distal end portion, and a flexible tube portion that is soft and has flexibility, the flexible tube portion being provided so as to be continuous with a proximal end side of the bending portion, a plurality of incorporated components being inserted in the insertion portion,

• wherein the bending portion comprises a first bending region including a plurality of first bending pieces pivotably joined so that the first bending region bends in the four directions, the plurality of first bending pieces being included in a distal end side of the bending portion, and a second bending region provided so as to be continuous with a proximal end side of the first bending region, the second bending region including a plurality of second bending pieces pivotably joined so that the second bending region bends in the four directions, the plurality of second bending pieces being included in the proximal end side of the bending portion;
• and
• wherein the flexible tube portion contains, in an interior space thereof,
• four first guide pipes disposed at respective positions in an inner circumferential face of the flexible tube portion, the positions corresponding to the four directions that are bending directions of the bending portion, the four first guide pipes allowing four bending wires corresponding to the bending directions of the bending portion to be inserted therethrough so that the respective bending wires freely advance/retract, the four bending wires each including a distal end fixed to a distal end of the first bending region and a proximal end fixed to a bending portion operation device provided at an operation portion provided so as to be continuous with a proximal end side of the insertion portion, and
• three second guide pipes disposed at predetermined positions in the inner circumferential face of the flexible tube portion, the three second guide pipes allowing three bent shape switching wires to be inserted therethrough so that the respective bent shape switching wires freely advance/retract, the three bent shape switching wires each including a distal end fixed to a distal end of the second bending region and a proximal end fixed to a bending portion bent shape switching device provided at the operation portion, and the three bent shape switching wires being configured to switch the second bending region to a contracted state by being simultaneously pulled in a direction toward the proximal end by the bending portion bent shape switching device,
• wherein from among the plurality of incorporated components, an incorporated component having a largest outer diameter is located between adjacent two of the first guide pipes in a circumferential direction,
• wherein positions of two second guide pipes of the three second guide pipes in the circumferential direction are set such that one of the two second guide pipes, one of the two first guide pipes, the incorporated component having the largest outer diameter, the other of the two first guide pipes and the other of the two second guide pipes are arranged in this order in the circumferential direction, and
• wherein a position in the circumferential direction where remaining one of the three second guide pipes is located at a position along the inner circumferential face of the flexible tube portion radially opposite the incorporated component having the largest outer diameter.