There is described an image forming apparatus, which make it possible to appropriately print each of a valid print object and an invalid print object. The apparatus includes: a printing section to conduct a printing operation based on the print data, so as to create the print product; and a control section to determine whether the digital signature is valid or invalid so as to control the printing operation, based on the determined result. When the plurality of print objects includes both a valid print object for which the digital signature is determined as valid and an invalid print object for which the digital signature is determined as invalid, the control section controls the printing operation, so as to enable the valid print object to be printed, based on the print data, while disable the invalid print object to be printed, based on the print data.