An injection needle assembly includes a needle tube, a needle hub holding the needle tube, a protector, an urging member, a sliding groove, and a sliding protrusion. The protector is movable between a first position of covering a needle tip of the needle tube and a second position of exposing the needle tip of the needle tube. The sliding groove is provided at one of the needle hub and the protector. The sliding protrusion is provided at the other of the needle hub and the protector and is inserted into the sliding groove to be slidable.
