A printer driver and an image forming apparatus for appropriately combining additional information (such as a stamp) and an original to print the combined image data. The printer driver according to one embodiment of the present invention, relates to a printer driver connected to a printer for registering form data transmitted from the printer driver, and for combining the registered form data and contents data. The printer driver transmits transparent data as form data and a command indicating that the form data is transparent data, to the printer.