The objective of the present invention is to provide a simple and accurate process for extracting an object from an image, which is used to impose a great load for an operator. According to the present invention, an image processing apparatus comprises an object extracting unit, for performing a predetermined process for image data for a position or an area that is designated and for extracting a specific object from an image, an outline part deciding unit, for selecting and authenticating an arbitrary segment of an outline obtained by the extracting unit, and an outline synthesis unit, for linking and synthesizing together the outline segments that are authenticated. Since a closed curve is formed by synthesizing the outline segments obtained by repeating the above process, and the outline of the object is thus determined, the outline segment that is extracted from the image and matches the correct outline of the object is sequentially selected and authenticated. The thus authenticated outline segments are linked and synthesized to gradually form the overall outline of the object.