A flexible display panel includes a glass substrate, a circuit layer disposed on the glass substrate and configured to drive a pixel, a light-emitting element layer disposed on the circuit layer, an encapsulation layer which covers the circuit layer and the light-emitting element layer, a polarizing plate disposed on the encapsulation layer, and a cover glass disposed on the polarizing plate, at least one of the glass substrate and the cover glass includes a buffer portion, the buffer portion includes an organic filler and glass, the glass of the buffer portion has a thickness less than or equal to a thickness of the glass substrate and includes a pattern of a specific shape, thus, rigidity of a folding portion in which the buffer portion is located can be increased due to the glass in the buffer portion.