An inertial input apparatus with six-axial detection ability, structured with a
gyroscope and an acceleration module capable of detecting accelerations of X, Y, Z axes defined by a 3-D Cartesian coordinates, which is operable either being held to move on a planar surface or in a
free space. When the inertial input apparatus is being held to move and operate on a planar surface by a user, a two-dimensional detection mode is adopted thereby that the
gyroscope is used for detection rotations of the inertial input apparatus caused by unconscious rolling motions of the user and thus compensating the erroneous rotations, by which the technical disadvantages of prior-art inertial input apparatuses equipped with only
accelerometer can be overcame and thus control smoothness of using the input apparatus is enhanced. In addition, when the inertial input apparatus is being held to operate in a
free space by a user, a three-dimensional detection mode is adopted for enabling the inertial input apparatus to detect movements of the same with respect to at most six axes defined by the 3-D Cartesian coordinates of X, Y, Z axes, that is, the rotations with respect to the X, Y, Z axes and the movements with respect to the X, Y, Z axes, and thus the inertial input apparatus is adapted to be used as an
input device for interactive computer games, In a preferred aspect, when the inertial input apparatus is acting as a 3-D mouse suitable to be used for briefing or in a
remote control environment, only the detections with respect to the X and Y axes acquired by the
accelerometer along with that of the
gyroscope are adopts and used as control signals for controlling cursor displayed on a screen, but the detection with respect to the Z-axis acquired by the
accelerometer is used as a switch
signal for directing the inertial input apparatus to switch between its two-dimensional detection mode and three-dimensional detection mode.