An object of the present invention is to provide: a thin imaging device in which a high image resolution is obtained and in which the resolution does not uniformly vary even when the shooting distance is changed; and a lens array used therein. The present invention relates to an imaging device comprising: a lens array 130 constructed by arranging in parallel a plurality of lens elements having optical power in at least one surface; and an image sensor 110 in which an optical image formed by an optical system having each of the lens elements is received by each of mutually different imaging regions each having a plurality of photoelectric conversion sections so that the optical image is converted into an electric image signal, wherein each lens element and the imaging region corresponding to the lens element constitute an imaging unit, while the imaging units have diverse imaging region areas. The present invention relates also to a lens array used therein.