To provide an automatic document feeder capable of stably feeding paper even when the tip of a document is bent by detecting the document by document detectors for detecting the size of the document and pressing the tip of the document.

In this automatic document feeder, the plurality of document detectors for detecting the size of the document are disposed at specified intervals at a document insert port in which the tip of the set document is inserted. Each document detector comprises an actuator swung by the tip of the set document and an energizing member energizing the actuator in a direction opposite to the direction in which the actuator is swung by the tip of the document. When the actuator is swung by the tip of the document, the tip of the document is pressed by the energizing force of the energizing member.