A production method for a medical instrument includes a step of producing a base material 3' which has a plurality of hollow fiber membranes 31 and forms a shape of a cylindrical body as a whole by integrating the plurality of hollow fiber membranes 31. In this step, each of the hollow fiber membranes 31 is caused to sequentially pass through a first point 101, a second point 102, a third point 103, a fourth point 104, and a fifth point 105 that are set on a core member 100. At this time, in an outward path heading toward the third point 103 from the second point 102, the hollow fiber membrane 31 reaches the third point 103 from the second point 102 at the shortest distance while being wound along the circumferential direction of the core member 100. Moreover, in a homeward path heading toward the fifth point 105 from the fourth point 104, the hollow fiber membrane 31 reaches the fifth point 105 from the fourth point 104 at the shortest distance while being wound along the circumferential direction of the core member 100 in the same direction as in the case of the outward path.
