An image forming device includes an image forming section, a sheet discharging section that discharges a sheet formed an image to outside of the device, a conveying path that conveys a sheet, a reading section that reads the image formed on the sheet on the conveying path leading from the image forming section to the sheet discharging section and outputs image data, and a control section that controls formation of the image to sequentially form images on sheets at a predetermined cycle, and the control section receives the image data, can execute a plurality of types of image analysis processes on the image data and can select and execute one or more types of image analysis processes which can be executed among the plurality of types of image analysis processes for a predetermined number of the sheets.