Disclosure is related to a method for sensing fast motion, a controller, and a related electromagnetic sensing apparatus. The method is applicable to a touch panel, in which a fast scan mode is introduced when a fast motion made by an electromagnetic stylus is sensed under a partial scan mode. Therefore, the scan mode is switched to the fast scan mode which is used to acquire coordinates of the stylus according to the electromagnetic signals generated by the stylus. After that, the process goes back to the partial scan mode for continuously sensing the location of the electromagnetic stylus, and determining any fast motion behavior. In one embodiment, in order to obtain the coordinates of the stylus when its moving rate exceeds a threshold, a moving direction may be firstly determined. The one or more sensing loops may be opened in the direction of movement.