Automatic Document Feeder and Image Reading Device

An image reading device, comprising:

• an automatic document feeder;
• and
• a reading portion configured to read a document carried to the reading portion,
• wherein the automatic document feeder comprises:
• a document tray on which a document to be read is placed;
• an output tray on which the document for which image reading is finished is placed;
• a roller which applies a carrying force to the document by rotating and contacting the document;
• a movable ejection flap configured to be movable between a first position where the document for which the image reading is finished is sunk into a position between the output tray and a bottom of a stacked document already staked on the output tray and a second position where the document is ejected on the output tray without being sunk into the position between the output tray and the bottom of the stacked document;
• and
• a switching unit configured to switch between a first motion of transmitting a driving force of a driving source to the movable flap and a second motion of transmitting the driving force of the driving source to the roller.