An imaging tube 210 includes an imaging lens and an illumination unit. A cap part 230 including a penetration part in which the imaging tube 210 penetrates is included at a leading end part of amain body part 220. A protective tube 212 that protects the entire circumference of the imaging tube 210 is attached to the imaging tube 210. A holding part 235 that holds an end part of the protective tube 212 with the imaging tube 210 is formed in the penetration part of the cap part 230. When being rotated in a first direction, the cap part 230 is moved in a direction opposite to a protruding direction of the imaging tube 210. When being rotated in a second direction opposite to the first direction, the cap part 230 is moved in the protruding direction of the imaging tube 210.
