The invention provides a device that appends a recognition point for image joining to the extracted image and a recognition element thereof. The device is to provide a plurality of holding slots on a holding platform. Besides, a plurality of positioning slots is provided at the sidewall of each holding slot so that the holding slot can accommodate and fasten an object to be image-taken. Then, when the image of the object is extracted by the segmented extractions, the image of the positioning slot can also be extracted so as to obtain an image with a recognition mark. Thus, the recognition mark can be used as a benchmark for image joining in order to obtain a whole image of the object. Moreover, the recognition element is to provide a positioning opening concavely at the side edge of a sheet-body, and the positioning opening is tiny. Therefore, the invention can achieve an effect of easy, rapid, and precise image joining.