An image forming apparatus obtains an interrupt execution instruction of an image forming job, the interrupt execution instruction including image data and execution information, suspends a prior image forming job being executed by using a first memory area, generates printable data by applying the execution information to image data of the suspended prior image forming job, writes the generated printable data in a second memory area, deletes the prior image forming job from the first memory area to free the first memory area, executes an interrupt image forming job of the interrupt execution instruction by using the first memory area, the prior image forming job having been deleted from the first memory area, and retrieves the printable data written in the second memory area and forms an image by using the retrieved printable data to execute the suspended prior image forming job.