PROBLEM TO BE SOLVED: To provide a polymer stent giving little influence to a living body while dwelling in a lumen and improving imaging/measuring accuracy of an MRI image, in which slit deformation giving a ratchet function is prevented and the ratchet function of the stent is maintained for a long period.SOLUTION: The polymer stent 1 is constituted by arranging a plurality of T shape unit parts 2 each comprising a head part 3 and body part 4 side by side and mutually coupling the same at the head parts and integrating the same. Hook shape protrusions 5 each having an oblique side and a vertical side are formed in one sides of the long sides of the body parts 4 of the respective unit parts 2 and slits in a vertical direction to the length direction of the body parts 4 are formed in the head parts 3. Width variable parts 7 are formed in the sides of the body parts 4 where the hook shape protrusions 5 are not formed or the tilting angle of the slits 6 are made variable at the end sides of the slits 6 of the head parts 3. Thus, the movement of the body part 4 in a direction reducing the diameter of the ring shape is stopped and the movement of the body parts 4 in a direction increasing the diameter of the ring shape is made possible when forming the ring part by rounding the body parts 4 and inserting the same into the slits 6.
