An image processing device configured to generate printing image data used during printing from input image data including a bar code constituted by a bar element and a space element that are a plurality of elements arranged based on a predetermined standard, includes a frequency distribution calculation unit configured to acquire widths of the plurality of elements respectively to calculate a frequency distribution of the widths of the plurality of elements, a standard width determination unit configured to determine a standard width of the plurality of elements of the barcode in the printing image data using the frequency distribution, and a correction unit configured to correct the widths of the plurality of elements of the barcode in the printing image data to the standard width.