A lens holding mechanism includes a lens barrel housing a lens that includes an entrance surface and an exit surface that are separated from each other in an optical axis direction, and a tapering surface, a diameter of which increases from the entrance surface side toward the exit surface side; a first abutting member that abuts, from the exit surface side, the lens housed in the lens barrel, and has an abutting portion that abuts the lens formed along a plane perpendicular to a reference axis of the lens barrel; and a second abutting member that abuts the tapering surface of the lens housed in the lens barrel, has an abutting portion that abuts the lens formed along a circle with a center point on the reference axis of the lens barrel, and holds the lens between the second abutting member and the first abutting member.