Abstract: In order to improve the quality of the drilling process in a surgical drilling apparatus for perforating the cranium including a drill plate which can be placed upon the cranium and a drill which is guided in the drill plate, it is proposed that the drill be accommodated in a mounting which is rotatably mounted on the drill plate, said drill being displaceable along the rotational axis and being accommodated so as to be non-rotatable relative to said mounting, and in that the drill be displaceable towards the mounting against the effect of a spring.