Provided is a medical hollow needle assembly which is increased in joint strength of a hollow needle to an outer cylindrical body, relative to a tensile load, and a method of manufacturing a hollow needle by which a manufacturing process can be simplified, and attachment of foreign matter to a hollow needle can be prevented. The medical hollow needle assembly (1) includes an outer cylindrical body (5) including a through-hole (5a), a hollow needle (3) having an outer peripheral surface partially including an outer reduced-diameter surface (6) having a diameter reduced toward a distal end side, and having a proximal end side disposed in the through-hole (5a), and an inner cylindrical body (7) including an insertion hole (7c) through which the hollow needle (3) is inserted, being disposed between the hollow needle (3) and the inner peripheral surface of the through-hole (5a), and joining the outer cylindrical body (5) and the hollow needle (3). The insertion hole (7c) of the inner cylindrical body (7) is provided with an inner reduced-diameter surface (9) reduced in diameter toward the distal end side, and engaging the outer reduced-diameter surface (6) of the hollow needle (3). A method of manufacturing a hollow needle (103) is used to be joined to an inner peripheral surface of a cylindrical body (107) provided in a medical instrument (101). The method includes a pressing step of punching out a plate body (110) having a predetermined shape from a metal plate, and rolling the plate body (110) to be molded into a tubular shape, and a joining step of joining a seam portion of the plate body (110) having been molded into the tubular shape. A surface of the plate body (110) is roughened in the pressing step to provide a roughened portion (106) at least partially on an outer peripheral surface of a portion joined to the inner peripheral surface of the cylindrical body (107) of the hollow needle (103).
