A balloon in which a rupture in a circumferential direction can be prevented from occurring, and a method of manufacturing the same is disclosed. The balloon is configured to be arranged on a medical catheter, and includes a dilatable cylindrical portion formed with a birefringent polymer material. A ratio of the number of orientation distributions, calculated by dividing the number of orientation distributions of the cylindrical portion in a circumferential direction by the number of orientation distributions of the cylindrical portion in an axial direction, is less than 2.
