PURPOSE: To keep the reliability by improving a contact property between a magnetic stripe provided on a bankbook of flexibility, or the like and a magnetic head without detriment to a life, etc., of the magnetic head.

CONSTITUTION: The mechanism is provided with a lower surface plate of a carrier path having a groove 100 to be abutted against the back surface of the bankbook under its open state and to be opened in the vicinity of the magnetic stripe 20 of this bankbook, a movable carrier guide 40 for pressing planely the opened page of this bankbook to the lower surface plate and the magnetic head 15 to be in contact with the magnetic stripe 20 of the bankbook through the groove 100 by prescribed pressure. Magnetic data is recorded and reproduced by this magnetic head 15 in contact with the magnetic stripe 20 of the bankbook held by the guide 40 and the lower surface plate 43.