The present invention relates to a stent for protecting a branch blood vessel at a branch-point lesion. The stent is inserted into and widened in a main blood vessel having the branch blood vessel extending in a slant from the branch-point lesion, thereby simultaneously expanding the main blood vessel and providing a smooth flow of blood towards the branch blood vessel. As a result, it is possible to simultaneously expand the main blood vessel and to sufficiently secure a passage from the main blood vessel towards the branch blood vessel. As such, the flow of blood is kept smooth. Further, after the stent is inserted into the main blood vessel, another stent, a guide wire, and related tools and catheter can be inserted in the direction of the branch blood vessel in a more accurate manner.