To provide an image-reading apparatus for preventing concentration difference due to pitch errors from standing out easily compared with the surrounding at the boundary of chips by an adhesion type image sensor.

The image-reading apparatus comprises an image-reading means that has a chip where a plurality of image pickup elements are arranged in a straight line, and the image information of a manuscript is fetched by an adhesion type image sensor where a plurality of chips are arranged in a straight line, an operation means for calculating image data to be interpolated between adjacent image pickup elements while sandwiching a boundary based on the image data of at least one image pickup element of each chip that is adjacent to the boundary between the adjacent chips when an interval where the image pickup elements are arranged in a straight line is set to be one pitch and the boundary image pickup element interval of image pickup elements that are adjacent while sandwiching the boundary between the adjacent chips is at least one pitch, and a control means for control for interpolating image data between the image pickup elements adjacent to the boundary by an operation result by the operation means.