A balloon for a catheter includes an inflation part, a connecting part, and a joint part. The inflation part extends in a cylindrical shape along an extension direction in an inflated state. The connecting part includes a first connecting part connected to the inflation part at a first point, a second connecting part connected to the joint part at a second point, and a third connecting part disposed between the first connecting part and the second connecting part. When the inflation part is in the inflated state, both a first angle and a second angle are larger than a third angle.
