Patent ID: 8159689

Claim:
An image forming apparatus that performs duplex printing in which image data is printed on both of a first face of a printing medium and a second face which is an opposite face of the first face, comprising: an input section that can input a series of pieces of image data having an order of printing that is determined in advance; a determination section that determines a difference in transfer efficiency between a first face and a second face of a printing medium after duplex printing; a judgment section that judges whether or not to change the order of printing based on the difference in transfer efficiency determined by the determination section; a control unit that controls the order of printing of image data based on the judgment; and an output section that prints image data on a printing medium, wherein in a case where the judgment section judges to change the order of printing, the output section prints image data on a printing medium in an order of printing that has been changed under control of the control unit.