An image forming apparatus includes a processor, and a storage controller that writes band data to a storage device and reads the band data. The processor: (a) generates a write-side process and a read-side process; (b) generates a write-side thread by the write-side process; (c) generates a read-side thread and a file read thread by the read-side process; (d) notifies the read-side process of an identifier within the storage device, and causes the storage controller to sequentially write the band data; and (e) requests the file read thread to cause the storage controller to sequentially read out the band data corresponding to the identifier and causes the storage controller to sequentially read out the band data and one or more subsequent band data.