Puncturing system for withdrawing a body fluid from the skin of a human or animal, comprising a needle element for piercing into the skin, a puncturing instrument, which includes a puncturing drive, by which a puncturing movement of the needle element, which is coupled to the puncturing drive by means of a coupling mechanism, is driven, wherein a) in a forward phase of the puncturing movement, the needle element is moved along a predetermined movement path in a piercing direction until its tip penetrates into the skin and, in a retraction phase of the puncturing movement, the needle element is retracted after reaching a reversal point corresponding to the puncturing depth in the skin, b) a predefined value of the puncturing depth is ensured by means of a puncturing depth reference element, which has a skin contact area, the predefined value of the puncturing depth being determined by the distance in the piercing direction between the skin contact area and the position of the tip of the needle element at the reversal point of the puncturing movement, c) the needle element and the puncturing depth reference element are separate elements which can be shifted relative to each other in the piercing direction, and the puncturing depth is adjustable by changing the distance (d) existing at the reversal point between the skin contact area of the puncturing depth reference element and the tip of the needle element, d) the puncturing depth reference element is coupled to the drive by the coupling mechanism in such a manner that it is moved together with the needle element at least during a part of the forward phase of the puncturing movement, and has a defined longitudinal position in the piercing direction in relation to the needle element at least at the reversal point of the puncturing movement, e) the coupling mechanism includes a needle element coupler comprising a needle element positioning part, which has a stop, cooperating with a corresponding stop of the needle element in such a manner that the longitudinal position of the needle element is at least at the reversal point of the puncturing movement determined by the contact of said stops (16b, 6b), the coupling mechanism includes a reference element coupler comprising a reference element positioning part, which has a stop, cooperating with a corresponding stop of the puncturing depth reference element in such a manner that the longitudinal position of the puncturing depth reference element is determined, at least at the reversal point of the puncturing movement, by the contact of said stops (17b, 10b), and the longitudinal position at which the positioning parts (16a, 17a) are located at the reversal point in relation to one another is changeable for adjusting the puncturing depth. a) in a forward phase of the puncturing movement, the needle element is moved along a predetermined movement path in a piercing direction until its tip penetrates into the skin and, in a retraction phase of the puncturing movement, the needle element is retracted after reaching a reversal point corresponding to the puncturing depth in the skin, b) a predefined value of the puncturing depth is ensured by means of a puncturing depth reference element, which has a skin contact area, the predefined value of the puncturing depth being determined by the distance in the piercing direction between the skin contact area and the position of the tip of the needle element at the reversal point of the puncturing movement, c) the needle element and the puncturing depth reference element are separate elements which can be shifted relative to each other in the piercing direction, and the puncturing depth is adjustable by changing the distance (d) existing at the reversal point between the skin contact area of the puncturing depth reference element and the tip of the needle element, d) the puncturing depth reference element is coupled to the drive by the coupling mechanism in such a manner that it is moved together with the needle element at least during a part of the forward phase of the puncturing movement, and has a defined longitudinal position in the piercing direction in relation to the needle element at least at the reversal point of the puncturing movement, e) the coupling mechanism includes a needle element coupler comprising a needle element positioning part, which has a stop, cooperating with a corresponding stop of the needle element in such a manner that the longitudinal position of the needle element is at least at the reversal point of the puncturing movement determined by the contact of said stops (16b, 6b), the coupling mechanism includes a reference element coupler comprising a reference element positioning part, which has a stop, cooperating with a corresponding stop of the puncturing depth reference element in such a manner that the longitudinal position of the puncturing depth reference element is determined, at least at the reversal point of the puncturing movement, by the contact of said stops (17b, 10b), and the longitudinal position at which the positioning parts (16a, 17a) are located at the reversal point in relation to one another is changeable for adjusting the puncturing depth.