To quickly adjust an image forming state by reading a reflected light in a read object and adjusting the image forming state of an image pickup section, on the basis of a measured read magnification.

A digital copying machine roughly consists of an image reader 100 and an image drawing unit 200. Reading an adjustment chart 114 by a CCD 102 after initial setting measures a read magnification of an optical system of the image reader 100. The measurement detects a difference between the measured magnification and an expected management (magnification offset). Then the magnification offset is converted into a shift of the optical system (consisting of a lens 106 and the CCD 102) on the basis of a table. Then a CCD micromotion mechanism 104 and a lens inching mechanism 108 are used to move the optical system, and then focus adjustment processing is completed. Thus, a reflected light in a read object is read, its read magnification is measured, and an image forming state of an image pickup section is adjusted on the basis of the measured read magnification.