A kind of medical electric drill includes a drilling tool, a guide member and a proximity sensor. Drilling tool includes that leader and a drill bit, drill bit are connect with handle. Guide member has a reflecting part, and guide member is to pilot bit. What handle is arranged in proximity sensor, and proximity sensor is opposite with guide member, and proximity sensor issues a transmitted wave to reflecting part, and transmitted wave is reflected back proximity sensor by reflecting part, and the direction of travel of transmitted wave is parallel with the extending direction of drill bit. Wherein, proximity sensor is by measuring the distance between handle and guide member, to calculate one of drill bit shift length.一種醫療用電鑽包含一鑽具、一導引件及一距離感測器。鑽具包含一把手及一鑽頭，鑽頭與把手連接。導引件具有一反射部，導引件用以導引鑽頭。距離感測器設置於把手，距離感測器與導引件相對，距離感測器發出一發射波至反射部，反射部將發射波反射回距離感測器，且發射波的行進方向與鑽頭的延伸方向平行。其中，距離感測器藉由量測把手與導引件之間的距離，來計算鑽頭之一位移距離。
