LENS UNIT

A lens unit includes: a lens including a lens part formed at the center of the lens, and a flange part that extends radially outward from the periphery of the lens part and includes a rear end surface on its rear side; a transparent spacer that is disposed behind the lens in the optical axis direction and used for focusing the lens part, the spacer including a front end surface that opposes to the rear of the lens, a spaced-apart part that opposes to the lens part and is spaced apart rearward in the optical axis direction from the lens part, and a bonded peripheral part that extends radially outward from the periphery of the spaced-apart part; and an adhesive that is disposed between the rear end surface of the flange part and the bonded peripheral part and bonds the lens and the spacer.