Abstract: This invention not only separates printing and barcode checking as independent processes but also simplifies printer processing to allow to print a large number of barcodes at high speed and to satisfactorily check barcodes. For this purpose, when a print control circuit unit (501) receives print information including a barcode, information associated with barcode checking is transmitted to a barcode checker unit (601) prior to printing. Upon actually printing an image including a barcode, when the printed barcode is conveyed to the position of a reader (603) in the barcode checker unit (601), an RD.sub.-- TRG signal is output to check the printed barcode. Upon reception of this signal, the barcode checker unit (601) reads the printed barcode a plurality of number of times at different positions, and when the normal reading ratio is low, it outputs an error signal to the print control circuit unit (501).