An electronic device according to various embodiments of the present disclosure includes a first housing, a second housing slidably coupled to the first housing, a flexible display configured to expand or reduce a size of a display area based on slide-in or slide-out of the second housing, a drive motor, a pinion gear coupled to the drive motor, a rack gear driven to engage with the pinion gear, and a rack cover coupled to the rack gear, wherein the rack cover includes a first blocking mechanism blocking foreign substances from entering the rack cover, and wherein the rack gear includes a second blocking mechanism blocking foreign substances from entering the rack gear.