A flexible display device includes: a flexible display unit configured to display an image; a flexible touch screen unit disposed over the flexible display unit; an insulating film interposed between the flexible display unit and the flexible touch screen unit, and a spacer formed between the flexible touch screen unit and the insulating film in order to maintain a distance between the flexible touch screen unit and the insulating film. A conductive layer is further formed over the insulating film and configured to touch the flexible touch screen unit when the flexible display device is bent. A degree of warpage of the flexible display device can be measured and thus can be utilized in various warpage events of the flexible display device by using warpage values.