To provide a page turning-over apparatus for a booklet capable of reading information and calibrating a sensor without operating vertically the booklet and a reference plate for calibration.

The page turning-over apparatus includes: a conveying mechanism for conveying the booklet on a conveying path; a page taking-up mechanism for taking up a page of the booklet conveyed by the conveying mechanism; a contacting roller for pressing and conveying a page below the page taken up by the page taking-up mechanism; a page number detecting sensor for detecting the number of the next page of the page taken up by the page taking-up mechanism; the reference plate for calibration used for calibration of the page number detecting sensor and provided on the upper part of the conveying path; and a linking mechanism which makes the contacting roller and the page number detecting sensor into one to convey the contacting roller onto the conveying path from the upper part of the conveying path, and to move it to the next page of the page taken up by the page taking-up mechanism, and simultaneously, moves the page number detecting sensor onto the conveying path from the upper part of the reference plate for calibration.