1. An image reading device comprising: document stacking means for stacking a document; document feeding means for picking up, one sheet at a time, the document stacked on the document stacking means; a curved transporting path through which the document picked up by the document feeding means is transported; and image reading means for reading an image from the document, the document stacking means including document lifting and lowering means for lifting or lowering the document stacked on the document stacking means within a range of a height of the curved transporting path, so as to feed the document to the document feeding means.