To provide an angle of rotation and a position to be grasped by a robot by extracting the profile of an object from an image taken for an object as a reference to obtain a histogram, taking the histogram as a template, and obtaining a tangential histogram from the profile of an image of the uppermost object of the overlapped objects to take matching with the template.

An input image by taking the image of an object by a television camera is differentiated to extract the profile. The center of gravity of the object is calculated, and the center of gravity is taken as a reference to trace the profile. The profile line coordinate which is the offset position, the tangential angle of each coordinate on the profile line, and the histogram of the tangential angle are obtained from the extracted center of gravity of the extracted profile to be registered as a template. While the correlation between the histogram of the tangential angle of the template image and the histogram of the tangential angle of an input image is taken, the angle is shifted to detect the angle of rotation. The temperate image is shifted while taking the correlation to extract the position of center of gravity from the profile picture elements in which the correlation between the tangential angle pattern of the input image and the template image is maximum.