1. An image-combining apparatus, comprising: a plurality of image processors provided for respective groups of images formed by grouping of the images in an image row into sequentially ordered images, each image in the image row having an overlapping portion that is a portion overlapping with a portion of another image, the image row having adjacent images that have the overlapping portions corresponding to a same portion of an object, the plurality of image processors concurrently performing processing to detect, by image-matching, combining-position information for combining a first image within one group and a second image in a position that is adjacent to the first image in the image row without any positional displacement; an image data transferring path to transfer an image of the overlapping portion of the second image belonging to a group different from the first image to the image processor that processes the first image having an overlapping portion corresponding to the same portion of the object, the image of the overlapping portion of the second image being a head of the images of a group corresponding to each image processor of the plurality of image processors; and a combination-information transferring path to transfer, between the plurality of image processors, combining-position information between the first image and the second image belonging to a group different from the first image, wherein each image processor of the plurality of image processors combines, based on the combining-position information self-detected and the combining-position information transferred via the combination-information transferring path, the images belonging to the corresponding group without any positional displacement while combining the images belonging to the corresponding group with an image belonging to another group without any positional displacement between adjacent images across different groups.