There is provided an imaging device which is small in light loss, is operable to suppress an occurrence of a stray light, and is operable to provide an image with a high quality as far as a periphery thereof. The imaging device operable to output an image of an object as an electrical image signal, comprising: a solid-state imaging sensor including pixels which are two dimensionally arranged on a first flat surface and each of which has a photo-electric conversion function; and a lens array including micro lenses two dimensionally arranged on a second flat surface separately provided so as to be parallel to the first flat surface, in which the solid-state imaging sensor includes an imaging area of unit including a plurality of pixels, and each of the micro lenses forms an optical image of the object on a corresponding imaging area of unit and satisfies a predetermined condition, arctan(L/f).ltoreq..theta., for a pixel, from among pixels included in an imaging area of unit corresponding to each micro lens, positioned farthest from an optical axis of a corresponding micro lens. Here, .theta. is a maximum angle of an incident light capable of entering a pixel, f is a focal length of a micro lens, and L is a diameter of a circle circumscribing an imaging area of unit corresponding to one of the micro lenses.