A catheter balloon having a base layer formed of a high-strength polymer and one or more covering layers formed over at least one surface of said base layer of the same flexible polymer or different flexible polymers having a elongation at break close to that of said high-strength polymer and being more flexible than said high-strength polymer, and has a wall thickness of 25 µm or thinner.A balloon having a base layer formed of a high-strength polymer and one or more covering layers formed over at least one surface of said base layer of the same flexible polymer or different flexible polymers more flexible than said high-strength polymer, and has a wall thickness of 25 µm or thinner, said covering layer or covering layers together bearing 10% or more part of the bursting stress of the balloon.A balloon catheter, especially blood vessel dilating catheter, equipped with any of the above balloons.
