A high-speed drill is an essential tool for any skull base surgery. However, if not appropriately used, it may cause serious inadvertent complications. Here, the authors present one case of surgery for a paraclinoid aneurysm of the internal carotid artery, in which tissue grabbing occurred during the drilling of the anterior clinoid process. This resulted in venous injury to the vessels of the nearby Sylvian fissure. Fortunately, the injury was manageable and caused no significant problems. The authors discuss the basic and other important points for the safe use of a high-speed drill. Discussion includes basic ways of drill handling, the appropriate selection of burrs, and so on. Bone curettage is also mentioned as a safe alternative tool.