An imaging apparatus comprises an optical magnification changing mechanism which optically changes a magnification of an image, and an electronic magnification change mechanism which reduces or expands a magnification with respect to image data by signal processing. The optical magnification changing mechanism is configured so that a magnification is discrete and a focal position changes together with a focal distance. The electronic magnification change mechanism carries out an interpolation process such that the number of pixels is increased with respect to a predetermined region of read image data during an expanding process, and carried out a process for discretely sampling a wide region as compared with a readout region obtained by the sampling provided when no magnification conversion is made, during a reducing process, thereby offsetting a change of the focal position in the optical magnification changing mechanism.