Abstract: An injection needle assembly includes a needle extended from a needle seat and a lockable needle arrangement which includes a locking platform radially extended from the needle seat, a needle enclosure foldably extended from the locking platform for enclosing the needle, and a locker unit including a first locker provided at the locking platform and a second locker provided at the needle enclosure, wherein the first and second lockers are engaged in a non-releasable manner to securely lock up the needle enclosure on the locking platform for ensuring the needle to be enclosed within the needle enclosure. Therefore, after the use of the needle for injection, the needle is enclosed and protected by the needle enclosure for preventing any cross infection.