Providing a medical hollow needle assembly with enhanced bonding strength of the hollow needle to the outer cylinder against a tensile load, simplifying the manufacturing process and preventing foreign matter from adhering to the hollow needle It is to provide a method for producing a hollow needle that can be used. An outer cylinder (5) provided with a through hole (5a) and a reduced diameter outer surface (6) that is reduced in diameter toward the distal end side are provided in a part of the outer peripheral surface, and the proximal end side is disposed in the through hole (5a). A hollow needle (3) and an insertion hole (7c) through which the hollow needle (3) is inserted, and is arranged between the hollow needle (3) and the inner peripheral surface of the through hole (5a). And an inner cylinder (7) for joining the outer cylinder (5) and the hollow needle (3), and the insertion hole (7c) of the inner cylinder (7) is directed toward the tip side. The medical hollow needle assembly (1) is provided with a reduced diameter inner surface (9) that is reduced in diameter and engages with the reduced diameter outer surface (6) of the hollow needle (3). A method of manufacturing a hollow needle (103) used by being joined to an inner peripheral surface of a cylindrical body (107) provided in a medical instrument (101), wherein a plate-shaped body (110) having a predetermined shape is formed from a metal plate. A pressing process for punching and rounding the plate-like body (110) into a tubular shape, and a joining process for joining seam portions of the plate-like body (110) molded into a tubular shape. The surface of the plate-like body (110) is roughened and at least part of the outer peripheral surface of the hollow needle (103) joined to the inner peripheral surface of the cylindrical body (107) is roughened. A process for producing a hollow needle, characterized in that a processing part (106) is provided.引張り荷重に対する中空針の外筒体への接合強度が高められた医療用の中空針組立体を提供することと、製造工程を簡略化するこ
