PURPOSE: To secure the reliable turning pages irrespective of a state of a passbook, by a method wherein in a matter turning the pages by rocking an arm by extending a feed belt, pressing force of the passbook of the feed belt is made freely adjustable by controlling turning torque of a rotary driving source rocking an arm.

CONSTITUTION: In an automatic page changing mechanism 1 which is used for a passbook entering machine, an arm 7 rockable freely centering around a supporting axis 9 is provided so as to extend in a width direction of a conveying path of the passbook. The arm 7 is rocked by operation of a motor 32 through a belt 35. Pulleys 10 are fitted turnably to both end of the arm 7 and the feed belt 12 is stretched extending over the pulley 10 and roller 11. Then, turning of the page of the passbook 5 is performed by the feed belt 12 and the turning of the page is constituted so that in the case where the turning of the pages is not detected, a quantity of a current to be fed to the motor 32 is increased by one stage, through which turning torque is increased and pressing force of the passbook of the arm 7 is increased.