To discriminate the opening/closing state of an opening/closing part without providing an opening/closing part detecting sensor by providing a guide member, to which a sheet printing a prescribed pattern is stuck, at the counter position of a reading means.

On an opening/closing cover 110, a thermal head 109 is arranged through a pressing spring 113 and a CIS (reading part) 107 is arranged by direct fixing. A white sheet 106 is stuck to a guide 105 forming a paper path 1. At both the ends of the sheet 106, wedge, triangle or slash-shaped patterns are printed in black outside a specified reading width on the side of CIS reading plane. The print pattern on the sheet 106 in the state of closing the opening/ closing cover 110 is preserved as an initial value. When the opening/closing part is opened, the form of the sheet 106 pressed by the CIS 107 is extended and a relative distance between a CIS reading point and the top end of the sheet is widened. Therefore, concerning an image signal different from the initial value, opening of the opening/closing part can be judged.