1. An imaging device including a lens having a single focal point on an imaging surface, the imaging device comprising: a solid-state imaging element on which a plurality of pixels are arranged in a matrix pattern at the imaging surface; and a light shielding layer including a plurality of aperture sections, wherein one of the plurality of aperture sections corresponds to one pixel including a plurality of light receiving regions and separates incident image light from a subject into diagonal image light with different directivity, the plurality of aperture sections is provided in one-to-one correspondence with the plurality of pixels and in same positions relative to each of a corresponding pixel of the plurality pixels, in a plan view of the solid-state imaging element, all of the plurality of light receiving regions of one pixel are disposed in areas where the aperture section corresponding to the one pixel does not exist, and none of the plurality of light receiving regions of the one pixel are disposed in an area where the aperture section corresponding to the one pixel exists, the plurality of light receiving regions include a plurality of photodiodes, and the plurality of photodiodes receive the diagonal image light with different directivity and photoelectrically convert the received diagonal image light such that the incident image light from the subject is simultaneously imaged in the plurality of photodiodes as a plurality of images.