An electronic device comprises housings including a first housing and a second housing configured to accommodate at least a portion of the first housing and guide sliding of the first housing, a flexible display including a first display area and a second display area extending from the first display area, and a monolithic support structure configured to support at least a portion of the second display area. The support structure includes a plate part and a plurality of bar-shaped parts protruding side by side from the plate part and disposed parallel to the plate part. The plate part and the plurality of bar-shaped parts are formed from a single monolithic structure. Each of the plurality of bar-shaped parts includes a second portion extending from the plate part and a first portion extending from the second portion, and a first width of the first portion is greater than a second width of the second portion. The plate part includes a plurality of openings located between adjacent ones of the bar-shaped parts.