Disclosed is an automatic document feeder for feeding a document to a document read surface. The document feeder has a first carrying mechanism for feeding a document toward the document read surface, a document leading mechanism for leading the document after passing above the document read surface, a second carrying mechanism for carrying the document led by the document leading mechanism, in a downstream direction, and a housing equipped with the first carrying mechanism, the document leading mechanism and the second carrying mechanism. The housing can be opened and closed relative to the document read surface. The document leading mechanism includes a movable member having an inclined surface that extends obliquely downward to direct a distal edge thereof toward the document read surface. The movable member can maintain the distal edge of the inclined surface at a substantially constant height relative to the document read surface.