A stent is disclosed, which is formed in a cylindrical shape and has a cavity portion, and is freely switched between an expanded state and a contracted state where the stent contracts to a central axis (O) side from the expanded state. The stent has an anchor portion which protrudes to a central axis (O) side relative to an inner surface surrounding the cavity portion in the contracted state, and which is displaced to the inner surface side in the expanded state relative to a protruded position in the contracted state.
