An image forming system includes plural image forming devices each of which forms an image corresponding to image data. Each image forming device includes a memory, a determining unit, a selecting unit, a specifying unit, and a transferring unit. The memory stores one or more pieces of image data. The determining unit determines whether or not usage of the memory is larger than a threshold. The selecting unit selects, if the determining unit determines that usage of the memory is larger than the threshold, a piece of image data to be transferred from among the pieces of image data stored in the memory. The specifying unit specifies a specific image forming device to which the selected piece of image data is to be transferred among the other image forming devices. The transferring unit transfers the selected piece of image data to the specific image forming device.