PROBLEM TO BE SOLVED: To provide a medical needle assembly enhanced in joint accuracy to the outer cylindrical body of a needle by pushing an inner cylindrical body accurately into a regulated position between the needle and the inner peripheral surface of a through hole.SOLUTION: A medical needle assembly comprises: an outer cylindrical body 5 having a through hole 5a a needle 3 having a base end side placed in the through hole and an inner cylindrical body 7 having a through hole 7c, into which the needle is inserted, for jointing the needle to the outer cylindrical body. The inner cylindrical body includes a cylindrical body part 7a placed between the needle and the inner peripheral surface of the through hole and a head 7b formed to have a larger diameter than that of the body part and formed to join one end of the body part thereby to abut against the leading end face of the outer cylindrical body.
