Provided is an expansible catheter balloon that has a spreadable outer diameter controllable easily in treatments for a calcific aortic stenosis, rheumatic and congenital aortic stenoses and others, and that can be effectively prevented from being freely shifted and can easily be fixed at a predetermined position. The catheter balloon includes a balloon having shoulder parts made of a non-expansible material or made low-expansible and an expandable waist part, and a catheter having a catheter body to which this balloon is fitted.
