An image forming apparatus (1) includes an image reading portion (13), an image processing portion (14), a storage portion (15,16), a storage selector portion (17), an image forming portion (18), and a control portion (10). The storage portion (15,16) includes a first storage portion (15) and a second storage portion (16) with greater vibration resistance than the first storage portion (15), and stores image data scanned by the image reading portion (13) and processed by the image processing portion (14). The storage selector portion (17) selects one of the first storage portion (15) and the second storage portion (16) based on the strength of mechanical vibrations during an operation of the apparatus (1), and a data size of the image data. The control portion (10) causes the image data to be stored in the storage portion (15,16) selected by the storage selector portion (17), and controls the image forming portion (18) to read the stored image data and form an image.