To provide an image output device which can secure a storage area necessary for performing processing in a mode other than an image output mode while storing as much file information as possible in storage means.

When an image output device is set in a memory printing mode, and the image output device has file information of an excessive image which cannot be stored in a predetermined capacity of file information storage area 67 (affirmative determination in a step S130), the image output device stores the file information of the excessive image in an unused area in a common storage area 68 which is to be used when the image output device is in a mode other than the memory printing mode (steps S140 to S180). Also, if the mode of the image output device is changed from the memory printing mode to the other modes (negation determination in a step S210), the image output device releases the unused area (a step S240). Thus, the image output device can secure a storage area necessary for performing processing in modes other than the memory printing mode while storing as much as file information as possible in a RAM.