PURPOSE: To accurately and smoothly feed one by one a plurality of stacked reading documents in particular having a mounting section to an image reading device, and simplify constitution.

CONSTITUTION: This mechanism has a pickup roller 24 and a delivery roller 28 for carrying the uppermost reading document 20 from a stacking position to a carrying section 26, as well as a return roller 30 laid so as to be faced to the roller 28 for returning other overlapped reading documents 20 to the stacking position. Furthermore, the mechanism is equipped with a unit 32 having the rollers 24 and 28, and a displacement means 34 to displace the unit 32 for separating the rollers 24 and 28 from the document 20.