A stent (1) to be implanted in a living body is formed substantially as a tube which has a form in which a plurality of wavy annular members (2) is arranged adjacently to each other in an axial direction of the stent (1) with the adjacent wavy annular members (2) connected with each other, has a diameter whose dimension is so set that the stent (1) can be inserted into a lumen inside a living body, and can be expanded when a force spreading radially from an inside of the tube is applied thereto. The wavy annular member (2) has parallel straight-line portions (11) extended in parallel with the axis of the stent (1) before and after the stent (1) expands. The stent (1) has connection portions (3) each connecting ends of the parallel straight-line portions (11) of the adjacent wavy annular members (2) to each other.
