An image forming device is provided that is capable of forming a proper integrated signal even when an image or a signal waveform is acquired from a pattern having the possibility of preventing proper matching, such as a repetition pattern, a shrinking pattern, and the like. In particular, the image forming device forms an integrated image by integrating a plurality of image signals and is provided with: a matching processing section that performs a matching process between the plurality of image signals; an image integration section that integrates the plurality of image signals for which positioning has been performed by the matching processing section; and a periodicity determination section that determines a periodicity of a pattern contained in the image signals. The matching processing section varies a size of an image signal area for the matching in accordance with a determination by the periodicity determination section.