To quickly and efficiently perform the assembling of a feeder by forming a complete paper carrier route and applying the feeder to a hard copy device adopting a flat floor document scanner at low cost.

In an automatic module type document feeder(ADF) 101 to be used for a flat floor input device such as a flat floor scanner or a flat floor copying machine, a pair of chassis constituted of three unit chassis provided with main chassis 401 installed between upper chassis 601 and lower chassis 801 for forming a complete paper route on the flat floor scanner or at the outside are provided so as to be releasable on a flat floor scanner when the scanner is mounted on the feeder 101.