An umbrella includes a shank, a fixed ring mounted on the shank, a movable ring movably mounted on the shank, a plurality of ribs each pivotally and detachably connected with the fixed ring, and a plurality of spreaders each pivotally and detachably connected with the movable ring. Thus, each of the spreaders and the ribs can be removed from the movable ring and the fixed ring respectively for replacement or maintenance, thereby enhancing the lifetime of the umbrella.