PURPOSE: To smoothly perform the suction and separation of a passbook to a cover by providing a valve mechanism introducing air into a suction cup during the suction of the cover to the suction cup.

CONSTITUTION: A passbook 30 is sent to a prescribed position to be stopped. Next, a lift device 4 is operated to lower a lift plate 5 and a suction cup 3 falls to the passbook 30 and, at the same time, clamp rollers 2a, 2a are raised. By this operation, only the suction cup 3 is pressed to a cover to suck only the cover. Subsequently, when the lift plate 5 is raised by operating the lift device 4, only the cover is released. In this state, a pin 9 is inserted in a gap and, at the same time, only the clamp roller 2a on a feed-in side is lowered and, next, air is introduced into the suction cup 3 by a valve mechanism. By this method, the cover of the passbook 30 is separated from the suction cup 3 to ride on the pin 9. By feeding the passbook in the direction reverse to the feed-in direction while the pin 9 is held as it is, paper turning-over operation is completed.