an outer circumferential surface configured to be in contact with a lens barrel; and

an inner circumferential surface forming a hole;

wherein a first length of the hole in a first direction, intersecting an optical axis, and a second length of the hole in a second direction, intersecting the optical axis are different from each other,

wherein a first distance from the outer circumferential surface to the inner circumferential surface, extended in the first direction, is less than a second distance from the outer circumferential surface to the inner circumferential surface, extended in the second direction along an entire thickness of the spacer in an optical axis direction, and

wherein the inner circumferential surface comprises a plurality of inclination portions having different slopes with respect to the optical axis.