An image reading device includes: an original table having a stationary original reading area and a moving original reading area on its top surface; an image reading unit provided inside the original table and moving the reading line in the direction of the width of the stationary original reading area and to the moving original reading area with the direction of the length of the stationary original reading area as the reading line; an original cover openably and closably provided on the original table so as to cover at least the stationary original reading area; and an ADF having an original conveyance path leading from an original tray by way of the moving original reading area to an original output tray. The image reading device reads originals of sizes larger than the readable stationary original size without any size increase of the device.