PURPOSE: To improve the operability of an original and to realize compact constitution by dividing an optical path into a horizontal and a vertical part and driving a couple of mirrors provided to the horizontal optical path part horizontally and also driving a lens provided to the vertical optical path part vertical for variation in magnification.

CONSTITUTION: A couple of the 2nd mirror 12 and the 3rd mirror 13 moves horizontally as one body in a table part 3, and the lens 18 moves perpendicularly in a leg column part 4. The 2nd mirror 12 and the 3rd mirror 13 are moved forth and back horizontally to vary the overall length of the optical by twice as large as they move, and the lens 18 is moved up and down vertically to vary the conjugate length of the optical system, thus performing desired magnification variation. Consequently, the whole unit is formed as a console type and the operability of an original is improved.