A sliding apparatus in which a first extension member and a second extension member are relatively movable in a longitudinal direction includes a restriction portion for restricting a movement range that allows the relative movement. The restriction portion includes: a projection portion that is formed integrally with the first extension member; and an engaging portion that is formed integrally with the second extension member. The projection portion has: a support portion; and a protrusion portion that is provided on a tip side of the support portion and is protruded toward the second extension member. The engaging portion has: a guide portion that guides the protrusion portion of the projection portion; and an abutting portion that abuts the protrusion portion. According to the present invention, it is possible to provide a sliding apparatus and a sliding structure that have a small number of parts, require no additional steps, significantly improve workability and productivity, and are capable of being disassembled in a simple manner and in a short time even after assembly.