PURPOSE: To simplify device constitution, to execute a detection processing of a motion at a high speed, and to detect an object motion in a real time by detecting the motion of a three-dimensional object by only solving a sample linear representative expression without executing a statistical processing.

CONSTITUTION: The motion of an object 100 is brought to image pickup by an image input part 101 such as a TV camera, etc., and as time elapses, plural pieces of images are fetched into an image recognizing part 102. The recognizing part 102 is constituted of a digital computer, etc., in advance, and from two pieces of images, and a shape data base which is measured in advance and accumulated in an image data base part 103, the three-dimenaional motion of the object between two pieces of images is calculated, based on a prescribed system. A result of calculation is outputted to a data output part 104 as a rotation quantum of a rigid body and a parallel moving amount. In this case, the calculation is executed by using a rotation around the X, Y and Z axes, a moving amount in the axial direction, and coordinate values of observation points P, P' as the prescribed system.