An imaging device includes a convex mirror for reflecting first incident light representing an object, the convex mirror having a shape of solid of revolution; an imaging mechanism for taking a reflected image represented by light reflected in the convex mirror; and an optical member for guiding the first incident light toward the convex mirror and guiding the reflected light toward the imaging mechanism, the optical member having an attenuation section for attenuating second incident light which is incident on an outer circumferential surface of the optical member in an opposite direction to the first incident light, passes through the optical member, is reflected by an inner circumferential surface of the optical member so as to be directed toward the convex rotational mirror, and is superimposed on the first incident light.