A production method for a medical instrument includes a plurality of integrated hollow fiber membrane producing a base material forming a cylindrically-shaped body. Each of the hollow fiber membranes sequentially passes through a first point, a second point, a third point, a fourth point, and a fifth point that are set on a core member. In an outward path heading toward the third point from the second point, the hollow fiber membrane reaches the third point from the second point at the shortest distance while being wound in the circumferential direction of the core member. Moreover, in a homeward path heading toward the fifth point from the fourth point, the hollow fiber membrane reaches the fifth point from the fourth point at the shortest distance while being wound in the circumferential direction of the core member in the same direction as in the case of the outward path.