PURPOSE: To reduce the size of a device by interlocking a member for detecting the presence or absence of a feed cassette to a locking mechanism for closing and engaging upper and lower bodies, and attaching and detaching the feed cassette thereby making both unlockable but making the same unlockable in the stage of mounting the cassette.

CONSTITUTION: When a feed cassette 7 is mounted to a lower body 13, an end part 31a of a lever 31 for detecting the presence or absence of the cassette is pressed and moves a connecting rod 33 to the right, thereby turning a locking lever 27 counterclockwise against a spring 30 and engaging the pawl 27a at the forward end thereof with an engaging hole 29. Therefore, the unlocking of the upper and lower bodies 13, 14 is infeasible, or the opening of the body 14 is infeasible. Thereupon, the operator detaches the cassette 7 and unlocks the bodies 13, 14 which are held locked by the arm 27. When an original platen 16 is retreated to a prescribed position, the operation of a knob 17 is made possible, and the body 14 is opened by a lifting spring mechanism 39.