An information input device and a method and medium for inputting information in three-dimensional (3D) space are provided. The information input device includes a movement signal input unit receiving a movement signal of the information input device under control of a user in a three-dimensional (3D) space, a movement extent calculating unit calculating an extent of a movement of the information input device by analyzing the received movement signal, a movement identification unit identifying a type of the movement by comparing the calculated extent of the movement with a predetermined threshold, and a signal processor processing the received movement signal so that an instruction corresponding to the identified type of movement is performed.