PURPOSE: A revolution sensing apparatus of a scanner is provided to make the rotation detection of the high speed / high accuracy by connectedly rotating the scanner. CONSTITUTION: A light emitting unit is located in the single-side of a photo interrupter(120). A light receiving unit(122) is located in the other side of the photo interrupter. The photo interrupter outputs the electric signal comparing to receive radiation intensity. A light blocking plate(130) revolves by a coupling of a rotation shaft(110) of a scanner on a task plane crossing lighting-emitting area and photo diode interval.
