PURPOSE: To provide an automatic document feeder(ADF) capable of avoiding delay of copying action time to the utmost.

CONSTITUTION: Document carrying speed is set at standard speed of either of speed V1, V2, V3 capable of maintaining copy productivity 100% at a prestep mode (steps S135, S136, S137). In the meantime, under the condition to delay copying action, that is, when a first document is carried to an exposure standard position (step S132) and a last document is discharged (step S139), they are respectively set at speed V0, V4 higher than the standard speed. Additionally, even at the time of carrying a double sided document and counting the number of sheets of the document, the document carrying speed is set at V0 (step S132).