With respect to an insert and an attachment member, after an insertion length of an optical fiber into a hollow tube is adjusted, it is possible to suppress the change of the insertion length of the optical fiber. An optical fiber (61) is inserted into an inside portion of a hollow tube of an insert and guides light emitted from a light source. A base end section (52) includes an optical fiber insertion part (53) used for inserting the optical fiber (61). An optical fiber fixing member (77) fixes the optical fiber (61) at a position spaced from a distal end of the optical fiber (61). The optical fiber insertion part (53) has a first portion (71) into which the optical fiber fixing member (77) is inserted. The first portion (71) has at least three protrusions protruding toward the center at positions spaced from each other in a circumferential direction. A size of the optical fiber fixing member (77) in a direction perpendicular to an insertion direction into the first portion (71) is larger than that of an inside portion of the first portion (71), and the optical fiber fixing member (77) is harder than the first portion (71).
