To provide a method for fabricating a dilatation balloon which has high hoop strength and which has satisfactory operability in treatment of blocking a smaller and more winding arterial vessel.

In the method for fabricating a treatment device which can be inserted to a living body and which can be dilated, removing and moving of polymer material dilatation balloon thins a selected place of a balloon wall of the biaxially orientated dilatation balloon, so that excimer laser beams (48, 68 and 88) are introduced to the balloons (20 and 98) at a selected place along the outer surface of the balloon.