A puncture needle comprising: a tubular sheath having a longitudinal axis; a needle tube that is arranged inside the sheath so as to be movable along the longitudinal axis and that has a needle tip at a distal end thereof; a protective tube that is arranged inside the needle tube so as to be movable along the longitudinal axis and that has a lumen into which a guide wire is inserted so as to be movable along a direction of the longitudinal axis; a needle slider that is connected to a proximal end of the needle tube; and a tube slider that is supported so as to be able to move in directions along the longitudinal axis relative to the needle slider and that is connected to the proximal end of the protective tube; wherein the needle tube has a step portion formed at a position midway along the needle tube in the longitudinal direction, the protective tube has a protrusion, which protrudes radially outward, on at least part of an outer peripheral surface thereof at a position which is nearer a proximal end side of the protective tube than the step portion is, and a distal end of the protective tube is positioned at a position so as to protrude from the distal end of the needle tube when the protrusion abuts the step portion from the proximal end side of the protective tube, the needle slider is provided with a locking portion that abuts the tube slider when the tube slider is moved forward toward the distal end side relative to the needle slider, and the protrusion is maintained in a state of pressing against the step portion when the tube slider is moved forward to a position where the tube slider abuts the locking portion. a tubular sheath having a longitudinal axis; a needle tube that is arranged inside the sheath so as to be movable along the longitudinal axis and that has a needle tip at a distal end thereof; a protective tube that is arranged inside the needle tube so as to be movable along the longitudinal axis and that has a lumen into which a guide wire is inserted so as to be movable along a direction of the longitudinal axis; a needle slider that is connected to a proximal end of the needle tube; and a tube slider that is supported so as to be able to move in directions along the longitudinal axis relative to the needle slider and that is connected to the proximal end of the protective tube; wherein the needle tube has a step portion formed at a position midway along the needle tube in the longitudinal direction, the protective tube has a protrusion, which protrudes radially outward, on at least part of an outer peripheral surface thereof at a position which is nearer a proximal end side of the protective tube than the step portion is, and a distal end of the protective tube is positioned at a position so as to protrude from the distal end of the needle tube when the protrusion abuts the step portion from the proximal end side of the protective tube, the needle slider is provided with a locking portion that abuts the tube slider when the tube slider is moved forward toward the distal end side relative to the needle slider, and the protrusion is maintained in a state of pressing against the step portion when the tube slider is moved forward to a position where the tube slider abuts the locking portion.