An image reading apparatus includes an image reading unit that includes light receiving units arranged in two-dimensional array and reads an image on an original in two-dimensional directions, a cover portion that forms a reader chamber with the image reading unit, and a read-start instruction unit that instructs the image reading unit to start reading the image on the original when the original is inserted into the reader chamber. The reader chamber has a space for containing the original therein, and forms an original insertion/ejection port with the cover portion for inserting or ejecting the original therethrough.