Abstract: An endoscope includes an active bending section and a passive bending section that are bendable and sequentially disposed from a distal tip; and a connection cylinder for connecting the active bending section and the passive bending section, wherein the active bending section and the passive bending section each include a plurality of articulated cylinders, a coil member, through which an operation wire to be operated for bending the active bending section is inserted, is fixed to the connection cylinder, and a cutout is formed in a vicinity of the coil member, the cutout enhancing a rotational freedom degree of an articulated cylinder, in the passive bending section, to be connected with the connection cylinder and to rotate.

Abstract: A treatment tool insertion channel of an endoscope, which is arranged through an inside of an insertion part that includes a flexible tube and a bendable part, includes a flexible inner tube, a spiral groove formed around the flexible inner tube over an entire length of the bendable part and the flexible tube, at least one coil wound along a bottom of the spiral groove, and at least one type of filler with which the spiral groove is filled. The treatment tool insertion channel includes a first portion that includes a part inside the bendable part and a second portion at a proximal end side of the first portion, the first portion being configured more flexible than the second portion.

Abstract: A treatment tool insertion channel of an endoscope, which is arranged through an inside of an insertion part that includes a flexible tube and a bendable part, includes a flexible inner tube, a spiral groove formed around the flexible inner tube over an entire length of the bendable part and the flexible tube, at least one coil wound along a bottom of the spiral groove, and at least one type of filler with which the spiral groove is filled. The treatment tool insertion channel includes a first portion that includes a part inside the bendable part and a second portion at a proximal end side of the first portion, the first portion being configured more flexible than the second portion.