An imaging device includes an arrayed imaging element group configured to receive light passing through a photographic lens, wherein the imaging element group includes a plurality of photographic elements used for photographic image data generation and a plurality of phase difference detection elements used for phase difference detection for focus detection of the photographic lens, each of the photographic elements and each of the phase difference detection elements include: an on-chip microlens configured to collect light passing through the photographic lens; a photoelectric conversion element configured to receive the light passing through the on-chip microlens; and an internal microlens disposed between the on-chip microlens and the photoelectric conversion element, the photographic element is configured such that an optical axis of the on-chip microlens matches an optical axis of the internal microlens, and the phase difference detection element is configured such that the optical axis of the on-chip microlens is shifted from the optical axis of the internal microlens.