An image processing device comprises an image data input means 2, an image data storage means 12 for storing the image data being input, an image data processing means 6 having multiple processing modes for outputting the stored image data, and a image data erasing means for erasing the image data stored in the storage means 12. The device further comprises erase count control means 8, 14 for controlling the number of times for erasing image data capable of having the number of times of erase set arbitrarily according to the security level required for each mode, and capable of having the set number of times of erase changed in mid-flow. Confidentiality is protected by performing erase operations repeatedly to the region storing the unnecessary image data according to the security level.