Provided are a region ensuring tool with which it is possible to ensure a field of view of a part to be operated on and a field of operation in a NOTES, and an endoscope which comprises the region ensuring tool. A region ensuring tool (10) which is used in natural orifice translumenal endoscopic surgery (NOTES) comprises a cylindrical main body part (11) having a hollow space. The hollow space of the main body part (11) is formed such that the cross-section area thereof gets bigger than the cross-section area of a shaft (2) of an endoscope (1), and it is possible for the main body part (11) to expand and contract in the direction which intersects the central axis (CL) of the hollow space. By making the main body part (11) protrude and expand from the leading end part of an outer cylinder (5), it is possible to ensure a field of view of an endoscope by the main body part (11) and a field of operation for an operation by the endoscope (1). By forming the main body part (11) to a size which can be housed in the outer cylinder (5) when contracted, it is possible to move the main body part (11) in the state of being housed in the outer cylinder (5) to a site where the operation, etc., is carried out, thus simplifying the positioning of the main body part (11) at the site where the operation, etc., is carried out.La présente invention concerne un outil de protection de région avec lequel il est possible de protéger un champ de visée dune partie sur laquelle une opération est prévue et un champ dopération dans une NOTES, et un endoscope qui comprend loutil de protection de région. Un outil de protection de région (10) qui est utilisé en chirurgie endoscopique transluminale dorifice naturel (NOTES) comprend une partie de corps principal cylindrique (11) ayant un espace creux. Lespace creux de la partie de corps principal (11) est formé de sorte que laire de section transversale de celui-ci soit plus grande que laire de section transversale dune tige (2) dun endoscope (1), e
