The memory capacity required for temporarily holding image data with respect to a printer is reduced, and loads involved in supplying image data, such as decoding and conversion processes, are dispersed and reduced. The apparatus divides image data in parallel with a main scanning direction by an image divider, stores the divided data in image data memory, and supplies the divided image data to image data temporary memory by an image data supply to perform a decoding process. In order to provide a matching with a process speed, the image data temporary memory temporarily retains the divided image data, and a printer prints an image on a sheet of paper on the basis of the divided image data stored in the image data temporary memory. A predictor predicts a supply process time by way of image data supply, and an image data supply control causes the image data supply to start the supply process of the divided image data at a time preceding the time for the start of the print process by the printer according to the time predicted.