A method of manufacturing a flexible display device is disclosed. The method includes arranging a first substrate having a plurality of depression units, forming a first plastic film in each of the plurality of depression units, forming a thin film transistor (TFT) on the first plastic film, forming a display device on the TFT, where the display device is configured to be electrically connected to the TFT, encapsulating an upper portion of the display device, cutting the first substrate, and separating the first substrate from the first plastic film.