A positionable mechanism includes a frame unit, an OIS unit, and a positioning unit that are mounted on a base unit. The frame unit is retractable with respect to the base unit between a storage position and a working position. The positioning unit is movable with respect to the OIS unit between an abutting position and a releasing position, and is subjected to a restoring force. When the frame unit is at the storage position, a pressing part of the frame unit presses the positioning unit to the abutting position where the positioning unit abuts against a movable carrier of the OIS unit. When the frame unit is at the working position, the positioning unit is restored to the releasing position and releases the movable carrier.