An imaging device includes an imaging element, a phase plate to modulate the optical transmission function of the optical image of the object, and an optical system for focusing the optical image modulated via the optical plate on the imaging surface of the imaging element, a spatial filter processing unit for image restoration processing to remove modulation by an optical phase filter by implementing two-dimensional spatial filtering processing on the image focused on the imaging surface of the imaging element. Modulation characteristics applied to the optical system by the phase plate are respectively different in the horizontal and vertical directions crossing at right angles along the flat surface of the imaging surface perpendicular to the optical axis.