An injection needle assembly includes a needle tube having a needle tip to be stuck into a skin, a first member, a second member, an adjustment portion, and a pressing force restricting member. The first member holds the needle tube and the second member holds the first member movably toward the axial direction of the needle tube. A discharge portion of the syringe is fitted into this second member The adjustment portion is provided at the periphery of the needle tube and includes a needle protrusion surface which abuts the skin in a case in which the needle tube is stuck to the living body. The pressing force restricting member is arranged between the first member and the second member, and restricts the pressing force added from the first member to the skin.