INSERTION DEVICE

The present invention discloses an insertion device, and the insertion device is provided with a bending preventer (15) having a first opening (15i) and a second opening (15t); an exterior member (6f)abutting a second surface (15b) side and connected to the bending preventer (15); and a protrusion (50) which, on the second surface (15b), is formed protruding circumferentially toward the exteriormember (6f) in order to fill a gap (S), and which, by abutting the external member (6f), can be elastically deformed obliquely in an outward direction (KO) of the bending preventer (15). 具有：防折件(15)，其具有第1开口(15i)和第2开口(15t)；外装部件(6f)，其抵靠在第2面(15b)侧而与防折件(15)连结；以及突起(50)，其用于填埋间隙(S)，在第2面(15b)呈周状朝向外装部件(6f)突出地形成，通过抵靠在外装部件(6f)而能够以朝向防折件(15)的外侧方向(K0)倾斜的方式弹性变形。