An optical magnification adjustment system being capable of minutely correcting magnification. A first lens 1 of plano-convex is installed on the side of an object surface 5, and a second lens 2 of concave-plano is installed on the side of a formed image surface 7. By controlling the center space d between the first lens and the second lens, the image is enlarged or reduced. The radii of curvature R2 and R3 of the convex surface of the first lens and the concave surface of the second lens are respectively set according to the following equations. R2=(1−n1)/&phgr;2 R3=(n2−1)/&phgr;3 where, &phgr;2 and &phgr;3 represent optical power, and n1 and n2 represent refraction indexes, respectively.