A magnification correction device 1 includes magnification correction optics 2, a pressure adjustment device 3 and a controller 4. The magnification correction optics 2 is formed in a shape of a box with a glass plate 20 and a bottom plate 11 positioned parallel to the glass plate 20 and a frame 10. The inside of the box is an air room 24 connected to a pressure adjustment device 3 via a connecting pipe 12 so that the pressure of the inside can be changed. The cylinder 30 is driven by a motor 35 via a linear movement unit 36 such as a ball screw and the motor 35 is controlled by a controller 4. The moving distance of cylinder 30, which is equal to the moving distance of the piston, is decided by the number of the revolutions of the motor 35, and the capacity of the closed circuit of the pressure adjustment device 3 is also decided.