Rotating image data of a subject which is composed of two-dimensional image data for each predetermined angle of rotation of the subject is stored in storing means. Reference image data and image data delayed from the reference image data are selected out of the two-dimensional image data for each predetermined angle of rotation of the subject which are stored in the storing means, and are successively read out. One of the reference image data and the delayed image data which are read out is outputted as a left eye image signal, and the other image data is outputted as a right eye image signal.