A mark position detection unit (200) includes an illumination unit (210) which illuminates an identification mark (102) provided on a leaf (70) with detection light (L1), and a detection unit (220) which detects a light (L2) emitted from the identification mark (102) which is illuminated with the detection light (L1). The illumination unit (210) includes a light source (211) which emits the detection light (L1). The detection unit (220) includes a polarizing filter (221) which filters the light (L2) emitted from the identification mark (102) and an imaging device (222) which detects a transmitted light filtered by the polarizing filter (221).
