An injection needle assembly (2, 60) comprising: a needle tube which has a needle point capable of puncturing a living body; a needle hub (22, 62) which holds the needle tube; a protector (26, 66) which is movable to a first position to cover the needle point of the needle tube and a second position to expose the needle point of the needle tube; a biasing member (27, 67) which biases the protector (26, 66) toward the needle point side of the needle tube along an axial direction of the needle tube; a retaining member (43, 83) which supports the protector (26, 66) to be movable along the axial direction of the needle tube and on which an abutment piece (29, 69) provided in the protector (26, 66) abuts when the protector (26, 66) is moved to the first position; and a restriction mechanism (28, 68) that restricts the protector (26, 66) from moving from the first position to the second position again after the protector (26, 66) moves from the first position to the second position and further moves from the second position to the first position, characterized by the injection needle assembly (2, 60) further comprising: an adjustment part (32, 72) which is provided around the needle tube, comes into contact with skin when the needle tube punctures the living body, and has a needle protrusion surface (32a, 72a) where the needle point of the needle tube protrudes, wherein the protector (26, 66) covers periphery of the adjustment part (32, 72) at the first position, wherein the needle hub (22, 62) includes a first member which holds the needle tube and which includes said adjustment part (32, 72) and wherein the first member comprises the retaining member. a needle tube which has a needle point capable of puncturing a living body; a needle hub (22, 62) which holds the needle tube; a protector (26, 66) which is movable to a first position to cover the needle point of the needle tube and a second position to expose the needle point of the needle tube; a biasing member (27, 67) which biases the protector (26, 66) toward the needle point side of the needle tube along an axial direction of the needle tube; a retaining member (43, 83) which supports the protector (26, 66) to be movable along the axial direction of the needle tube and on which an abutment piece (29, 69) provided in the protector (26, 66) abuts when the protector (26, 66) is moved to the first position; and a restriction mechanism (28, 68) that restricts the protector (26, 66) from moving from the first position to the second position again after the protector (26, 66) moves from the first position to the second position and further moves from the second position to the first position, characterized by the injection needle assembly (2, 60) further comprising: an adjustment part (32, 72) which is provided around the needle tube, comes into contact with skin when the needle tube punctures the living body, and has a needle protrusion surface (32a, 72a) where the needle point of the needle tube protrudes, wherein the protector (26, 66) covers periphery of the adjustment part (32, 72) at the first position, wherein the needle hub (22, 62) includes a first member which holds the needle tube and which includes said adjustment part (32, 72) and wherein the first member comprises the retaining member.