A mark position detection unit includes an illumination unit which illuminates an identification mark provided on a leaf with detection light, and a detection unit which detects a light emitted from the identification mark which is illuminated with the detection light. The illumination unit includes a light source which emits the detection light. The detection unit includes a polarizing filter which filters the light emitted from the identification mark and an imaging device which detects a transmitted light filtered by the polarizing filter.
