The invention relates to an instrument for preparing and/or machining a femoral head (11) embodied on a femoral neck (19). Said instrument comprises tactile forceps (91) that are provided with two forked levers (13, 15) and two tactile jaws (23, 25), each of which is assigned to one of the forked levers (13, 15). The forked levers are interconnected at a fulcrum (93). The inventive instrument features a manipulating end and a working end. The tactile jaws are located at the working end of the instrument. A guiding element (28) is provided which encompasses a centering pin (21) and is mounted and/or guided at least at two points (105, 107) spaced apart from each other in the direction of the centering pin (21) in such a way that the centering pin (21) always lies on a central plane (12) of the tactile forceps (91) regardless of an opening angle of the tactile forceps (91), said central plane (12) containing the fulcrum (93). The bearing and/or guiding points (105, 107) are directly and/or indirectly hinged to the tactile forceps (91).