A flexible display device including a substrate; a driving element layer including a plurality of thin film transistors on the substrate; a display element layer including organic light-emitting diodes electrically connected to the thin film transistors on the driving element layer; a light transmissive layer on the display element layer and configured to adjust a neutral plane of the flexible display device to lie at the driving element layer and the display element layer when the flexible display device is bent; and a back plate film attached to a back side of the substrate and having a cut portion formed in a center region where the flexible display device is bent.