To economize resources and effectively utilize the resources by setting a 3rd mode in the case not only a 1st mode execution means but also a 2nd mode execution means can not be used when a priority image forming mode is a 1st mode.

A CPU 100 performs input processing by an operation panel 4 and copying control by a control part 101 in accordance with a priority copying mode stored in a RAM 102 according to a program stored in a ROM 103. In copying mode initialization processing, a copying mode is set to any of a double-sided copying mode being the 1st mode execution means, a one-sided copying mode being the 3rd mode execution means, and a 2-in-1 copying mode being the 2nd mode execution means based on the priority copying mode stored in the RAM 102. When a double-sided copying function can not be used in the case the priority copying mode is the double-sided copying mode, the 2-in-1 copying mode is selected and set preferentially to the one-sided copying mode.