To obtain a scanner assembly for correcting the fluctuation of a scanning optical part along a rotary shaft by substantially eliminating a defective image deversely affecting the image quality of photosensitive film after being developed.

The scanner assembly is provided with a light source 88 for generating light beams, a reflection system 82 rotatable around the rotary shaft and a toric lens 118. The reflection system is composed of the scanning optical part defined by a pentagonal prism 92 and a cylindrical lens 116. The light beams are reflected on the second reflection surface 98 of the pentagonal prism by the first reflection surface 96 of the pentagonal prism. Also, the light beams are reflected on the second reflection surface, so that an image is formed on an image material through the cylindrical lens and the toric lens. The fluctuation of a reflection system along the rotary shaft caused by a bearing and mechanical inaccuracy at the driving mechanism of the reflection system is corrected by the cylindrical lens and the toric lens together with the pentagonal prism.