PURPOSE: To reduce the number of parts and the assembly man-hour of a lens barrel by forming an acute projected line part on the inner peripheral surface of a lens spacing ring keeping space between the lenses in the lens barrel specified space and using the projected line part also as a light shielding plate for preventing flare.

CONSTITUTION: Plural lenses 18 are arranged in order along an optical axis 20 in the lens barrel 16, and the lenses 18 are kept by the lens spacing ring 22 so that the space between the lenses 18 may be the specified one. The projected line part 22A whose cross section is triangular is formed on the inner peripheral surface of the ring 22. In order to use the ring 22 also as the light shielding plate for preventing the flare, the ring 22 is formed so that the inside diameter L of the projected ring part 22A may be equal to the inside diameter L of the light shielding plate in size. Namely, the projected line part 22A of the ring 22 is used also as the light shielding plate for preventing the flare.