An image processing apparatus that stores print data in a cache memory while preventing performance from being degraded by cache flushing. The image processing apparatus includes a cache for storing print data, and an SD card for storing the print data stored in the cache. A cache controller of a CPU transmits an SD card write request for storing the print data stored in the cache into the SD card to a secondary storage device access controller. When the SD card write request is received after printing of the print data has been normally terminated, the secondary storage device access controller disables execution of the storage processing.