PURPOSE: To provide an automatic paper feeder excellent in the ratio of performance/cost by reducing the number of part items of a cage body, facilitating assembling of a mechanism part, and avoiding the lowering of accuracy by thermal expansion in the automatic paper feeder of an information processor using a sheet-like medium.

CONSTITUTION: Paper sheet guide surfaces 2 or the like are integrally formed on synthetic resin upper and lower frames 1 or the like to sandwich a paper sheet passage crossing a device, and a paper feed roller device is directly shaft- supported. A side wall of a lower frame is formed as a double structure, and a side wall 7 of an upper frame 1 is situated inside of an inside plate on the side wall of the lower frame. A roller shaft of the paper feed roller device is shaft-supported on the inside plate and the side wall 7 of the upper frame. An upper surface of a paper sheet is guided by the tip side of a paper feeding directional comb-shaped reinforcing rib 11 arranged on the upper frame 1. A driven roller of a feed roller is shaft-supported on a central part of the frames, and is brought into push contact with a driving roller 5a by bending elastic force of the resinous frames.