A flexible display device is disclosed. The disclosed flexible display device includes a flexible substrate; a thin film transistor on the flexible substrate; and a light emitting diode or a liquid crystal capacitor connected to the thin film transistor. The flexible substrate includes: a first base layer; a second base layer on a first surface of the first base layer; and a third base layer on a second surface of the first base layer. A surface hardness of the second base layer is greater than a surface hardness of the third base layer, and an adhesion strength of the third base layer is greater than an adhesion strength of the second base layer.