An imaging apparatus is disclosed for diagnosis, which can display a tomographic image of biological tissues using ultrasound waves and light, and wherein the imaging apparatus can accurately perform diagnosis on biological tissues, in which while a user is suppressing a visual loss between an ultrasound cross-sectional image and an optical cross-sectional image, the user can check his or her interest site in the biological tissues by using both the ultrasound cross-sectional image and the optical cross-sectional image, without changing the user's viewpoint position. Therefore, in a magnifier mode, a circular frame indicating a magnifier whose position can be freely changed by the user inside an image display region is displayed inside the image display region. Then, an IVUS cross-sectional image is displayed in a region outside the circular frame within the image display region, and a partial image of an OCT cross-sectional image is displayed inside the circular frame.
