An insertion apparatus includes: a bend preventing member having a first opening and a second opening； an exterior member connected to the bend preventing member in a state where the exterior member abuts against a second surface side, and a projection which is formed on the second surface circumferentially in a protruding manner toward the exterior member, the projection being elastically deformable such that the projection is inclined in an outside direction of the bend preventing member by making the projection abut against the exterior member.
