An imaging method for an X-ray CT apparatus having an X-ray source and an X-ray detector disposed to face the X-ray source with a subject placed therebetween, for rotating at least one of the X-ray source and X-ray detector around the subject and detecting X-rays emitted from the X-ray source toward the subject by the X-ray detector, comprises the steps of: defining a reconstruction plane for the subject in a plane non-parallel to a plane formed by rotation of at least one of the X-ray source and X-ray detector around the subject; scanning the subject by emitting cone-shaped X-rays from the X-ray source; and reconstructing a tomographic image of the subject based on the defined reconstruction plane.