A method of manufacturing a flexible display device includes: forming an integrated circuit chip, a flexible printed circuit board and a frontplane laminate over a driving substrate; adhering a front protective layer over the frontplane laminate and the flexible printed circuit board, such that the front protective layer is in contact with the frontplane laminate, in which the front protective layer has a first opening corresponding to the integrated circuit chip; and filling a second adhesive into the first opening and covering an upper surface, a side surface or a combination thereof of the integrated circuit chip. A flexible display device is also provided.