A medical drilling device for drilling of human or animal tissue carries a drill (7) that is electrically contacted by a bore electrode (9) and a backing electrode (10). Both electrodes (9, 10) are charged by a resistance-measuring device (11) in a way, that electrical resistance of tissue (2, 3, 4), preferably impedance, as measured between the drill (7) and the backing electrode (10) becomes measurable. By means of a monitoring device (13), the surgeon is provides with information about the type of the respective tissue and the depth of drilling.
