A flexible display device includes: a flexible panel having a bending portion that is configured to bend about a radius with respect to an inner peripheral surface of the bending portion, and a housing supporting the flexible panel. The bending portion has one or more recesses at the inner peripheral surface of the bending portion, and an entry width of each of the recesses, a number of the recesses, and a thickness of the flexible panel meet the relation equation of πd=nG, where G denotes the entry width of each of the recesses, n denotes the number of the recesses, and d denotes the thickness of the flexible panel.