Balloon for catheter

A balloon for a catheter comprising:

• an inflatable portion having a tube shape and extending in an extending direction;
• a distal end connecting portion being a portion extending from a first distal end portion of the inflatable portion that is on one side in the extending direction of the inflatable portion, to a second distal end portion of the balloon, a diameter of a third proximal end portion of the distal end connecting portion connected to the inflatable portion being larger than a diameter of the second distal end portion of the balloon that is on the opposite side from the third proximal end portion connected to the inflatable portion;
• and
• a proximal end connecting portion being a portion extending from a first proximal end portion of the inflatable portion that is on another side in the extending direction of the inflatable portion to a second proximal end portion of the balloon, a diameter of a third distal end portion of the proximal end connecting portion connected to the inflatable portion being larger than a diameter of the second proximal end portion of the balloon that is on the opposite side from the third distal end portion connected to the inflatable portion, wherein
• wherein the balloon for the catheter includes an inner side thick film portion and a thin film portion having differing thicknesses from each other,
• the thickness of the inner side thick film portion is greater than the thickness of the thin film portion,
• an inner surface at the inner side thick film portion protrudes further inward than an inner surface at the thin film portion, in a radial direction centered on a center axis extending in the extending direction and passing through a center of the inflatable portion,
• an outer surface at the inner side thick film portion does not protrude further outward in the radial direction than an outer surface at the thin film portion,
• the inner side thick film portion is provided at the inflatable portion, the distal end connecting portion, and the proximal end connecting portion,
• the inner side thick film portion extends along the extending direction from the second distal end portion to the second proximal end portion,
• the thickness of the inner side thick film portion of the distal end connecting portion becomes gradually thinner from a portion connected to the first distal end portion of the inflatable portion toward the second distal end portion, and
• the thickness of the inner side thick film portion of the proximal end connecting portion becomes gradually thinner from a portion connected to the first proximal end portion of the inflatable portion toward the second proximal end portion.