A cranial drill comprises a main machine, a reducer and a locking seat that are successively threadedly connected, wherein a drill transmission rod interconnected to the output shaft of the reducer is inserted in the locking seat. The main machine comprises a handle (1) in the lower portion, and a containing part (2) in the upper portion having a stator and rotor (5) of a DC electric motor provided therein, the wall (4) of the containing part defining the housing of the stator of the DC electric motor. This cranial drill is simple in structure with the wall (4) of the containing part (2) defining the housing of the stator of the electric motor, thus the volume and the weight are reduced. It is safe in operation, without the risk of the electric motor falling out. And its waterproof performance is good, utilizing materials and processes of waterproof technology and an integrative design.
