[Problem]Provided are a balloon catheter in which the fracturing of the vicinity of a proximal opening portion formed by an inner shaft can be prevented, and a method for manufacturing a medical elongated body.[Means for Resolution]A distal side of an inner shaft 140 included by a balloon catheter 10 is disposed in a lumen of an outer distal shaft 120, and a proximal side of the inner shaft 140 is disposed on an outer surface of an outer proximal shaft 130, and the inner shaft 140 forms a proximal opening portion 105 which opens on an outer surface side of the outer proximal shaft 130. The inner shaft 140 has a first region 150A and a second region 150B disposed on a proximal side of the first region, in a range from a proximal end 123 of the outer distal disposed on the outer surface of the outer proximal shaft to the proximal opening portion. The first region is fixed to the outer surface of the outer proximal shaft. The second region is not fixed to the outer surface of the outer proximal shaft.
