A lens barrel which is capable of attaining further reduction of thickness and size of a lens barrel by making effective use of accommodation spaces for barrier blades. In the lens barrel, barrier blades openably covers an image-taking by changing over its position between an image-taking position and a standby position. Accommodation spaces receive the barrier blades therein, respectively, when they are open. When the lens barrel is switched from the image-taking position to the standby position, a rectilinearly-moving restriction barrel relatively moves closer to the barrier blades in an optical axis direction, and at this time, arch-shaped portions of the rectilinearly-moving restriction barrel enter the accommodation spaces.