In the original reading apparatus configured to store the image data in the image storing unit such as temporary storage memory, time required to complete the overwriting for erasure is reduced. The image data read by the image reading unit is stored in the image data storing unit and the stored image data is output. To hold data stored in the image data storing unit, refresh processing, which is to perform processing intermittently required to hold the data stored in the image data storing unit, is performed at a predetermined execution frequency. After the image data is output, frequency to execute the refresh processing is reduced as compared to a predetermined execution frequency to perform writing of the dummy data.