Problem: To extract an image including a desired area included in a moire area from an image in which a sheet that includes the moire area has been imaged. An image area extracting device 1 extracts an image area from an image in which a sheet has been imaged provided with a first layer section having a first pattern including a plurality of drawn lines extending in a first direction, a second layer section overlapping the first layer section and including a plurality of drawn lines extending in a second direction that is different from the first direction, and a low adhesion section where adhesive force is lower than that of an adhesive section and an adhesion section arranged on an adhesive surface opposite a surface facing the first layer section and the second layer section. At this time, the image area extracting device 1 executes processing that includes acquiring sheet image data showing a sheet image including a sheet imaged so as to include a moire area where a moire is created by overlaying the first pattern and the second pattern is acquired, extracting the moire area from the sheet image, extracting a non-fixing area where the low adhesion section is arranged based on a size of a fixing area where the adhesion section is arranged, and outputting non-fixing area image data showing a non-fixing area image including the non-fixing area.