Cranial perforator comprising: - a rotating element capable of being fixed to a driving element; - a first drill-head and a second drill-head capable of rotating about a same axis and of moving in translation along said axis relative to each other and each relative to said rotation element and each having, at one of its extremities, a plurality of teeth (21; 31), said first drill-head being housed within said second drill-head , - clutch means disposed on said first drill-head and said rotating element making it possible, in an engaged position, for said first drill-head to be linked in rotation with said rotating element when said rotating element is put into rotation and making it possible, in an idle position, for said first drill-head not to be linked in rotation with said rotating element when said rotating element is put into rotation; - means of disengagement from said engaged position to said idle position; and - a casing partly encasing said second drill-head , said second drill-head being linked to said casing by a sliding pivot link and comprising a supporting surface capable of abutting said casing when said second drill-head is driven by a movement of translation moving away from said rotating element along said axis ; characterized in that : said first drill-head comprises at least one first supporting surface capable of abutting said second drill-head when said first drill-head is put into rotation about said axis and, at least one second supporting surface capable of abutting said second drill-head when said first drill-head is driven by a motion of translation moving away from said rotating element along said axis ; and in that said casing is fixed at one of its extremities to said rotating element . - a rotating element capable of being fixed to a driving element; - a first drill-head and a second drill-head capable of rotating about a same axis and of moving in translation along said axis relative to each other and each relative to said rotation element and each having, at one of its extremities, a plurality of teeth (21; 31), said first drill-head being housed within said second drill-head , - clutch means disposed on said first drill-head and said rotating element making it possible, in an engaged position, for said first drill-head to be linked in rotation with said rotating element when said rotating element is put into rotation and making it possible, in an idle position, for said first drill-head not to be linked in rotation with said rotating element when said rotating element is put into rotation; - means of disengagement from said engaged position to said idle position; and - a casing partly encasing said second drill-head , said second drill-head being linked to said casing by a sliding pivot link and comprising a supporting surface capable of abutting said casing when said second drill-head is driven by a movement of translation moving away from said rotating element along said axis ; said first drill-head comprises at least one first supporting surface capable of abutting said second drill-head when said first drill-head is put into rotation about said axis and, at least one second supporting surface capable of abutting said second drill-head when said first drill-head is driven by a motion of translation moving away from said rotating element along said axis ; and in that said casing is fixed at one of its extremities to said rotating element . <EOS>