PURPOSE: To correct erroneous transport of original sheet likely to occur at the time of switching-back by allowing the sheet to run against a feed roller and thereby forming a loop.

CONSTITUTION: In separation stage, a separation drive motor is turned on to separate only the undermost lying one of the original pages in a bundle, and when it proceeds in a sheet bus Ia and a sheet sensor S1 senses the leading edge of the sheet, a separation loop timer is started and, after completion, said separation drive motor is turned off to allow the leading edge of the sheet to run against the nip part of feed rollers 6, 6a, to be followed by stop of the sheet when such a condition is attained that a loop corresponding to a certain amount is formed. This can correct eventual skew likely to occur at the time of separation to contribute to prevention of jamming as well as to saving recording material.