Provided is an image forming system including an image forming apparatus, and a processing apparatus that is provided in the image forming apparatus, wherein the processing apparatus includes a memory that stores at least image data, a determiner that determines degradation status of the memory, and an interface unit that is used for connection of a processing-apparatus-side display device which displays information of the processing apparatus, the image forming apparatus includes an image-forming-apparatus-side display that displays information of the image forming apparatus, and the processing apparatus causes the image-forming-apparatus-side display to display an alert in a case where the determiner determines that the degradation status satisfies a predetermined condition, when the processing-apparatus-side display device is not connected to the interface unit.