Endoscope

1. An endoscope comprising: an insert portion having a bending portion for bending operation and a flexible soft portion; a ring connected between the bending portion and the soft portion, the ring being of a hard material that is less flexible than the flexible soft portion; an inflatable/deflatable balloon in which a distal end of the balloon is at least partially attached on the ring; and a supplying/sucking opening provided in an outer surface of the ring, the supplying/sucking opening supplying and sucking fluid to and from the balloon, wherein an inner portion of the ring is formed so that a thickness of a first portion where the supplying/sucking opening portion is provided is thicker than that of a second portion other than the first portion of the ring of hard material, wherein a tube member is connected to the supplying/sucking opening at the first portion where the thickness is thicker than other portions, and wherein an end of a tip side of the balloon is fixed to the ring and an end of a proximal side of the balloon is fixed to the soft portion.

2. The endoscope according to claim 1 , wherein the tube member is bent at a midpoint thereof, so that a proximal side end opposite to the supplying/sucking opening is arranged in parallel to the ring axis, and wherein the proximal side end of the tube member has a flexible tube connected.

3. An endoscope comprising: a bending portion for bending operation; a flexible soft portion; a metal ring; an inflatable/deflatable balloon in which a distal end is attached on the metal ring; and the metal ring connected between the bending portion and the flexible soft portion for connecting the bending portion to the flexible soft portion, the ring having a supplying/sucking opening provided in an outer surface thereof for supplying and sucking fluid to and from the inflatable/deflatable balloon, wherein an inner portion of the ring is formed so that a thickness of a first portion where the supplying/sucking opening portion is provided is thicker than that of a second portion other than the first portion of the metal ring, and wherein a tube member is connected to the supplying/sucking opening at the first portion where the thickness is thicker than other portions, and wherein an end of the balloon closer to the bending portion is fixed to the metal ring, and an end of the balloon closer to the flexible soft portion is fixed to the flexible soft portion.

4. The endoscope according to claim 3 , wherein the tube member is bent at a midpoint thereof, so that a proximal side end opposite to the supplying/sucking opening is arranged in parallel to the ring axis, and wherein the proximal side end of the tube member has a flexible tube connected.