PURPOSE: To reduce the degradation of the capacity of a lens for enlargement and reduction, by moving the lens orthogonally to the advance directiono of light to perform enlargement and reduction with one lens.

CONSTITUTION: At a reduction magnification time, a base 24 is moved in the X direction to bring the second and the third mirrors 12 and 13 to positions 12' and 13' indicated by virtual lines, and a base 21 is moved in the Y' direction to shorten the optical length from a lens 17 to a focal surface, and the conjugate length is increased in accordance with a focusing magnification. At an enlargement magnification time, the lens 17 is moved in the Y direction and is brought to a position 17' indicated by a vertual line, and the base 24 is moved in the X direction to bring the second and the third mirrors 12 and 13 to positions 12' and 13' indicated by vertual lines, and the base 21 is moved in the Y direction to extend the optical path length from the lens 17 to the focal surface. Thus, the direction of incidence to the lens 17 is reverse, and the optical length from the lens 17 to the focal surface is increased, and the conjugate length is increased in accordance with the focusing magnification.