A method for manufacturing a flexible display device includes: manufacturing a flexible substrate on a substrate by: forming a first organic layer on the substrate, removing foreign particles formed on the first organic layer and forming a recessed first repair groove in the first organic layer, forming a first inorganic layer on the first organic layer, forming a second organic layer on the first inorganic layer and forming a second inorganic layer on the second organic layer, forming a display for displaying an image on the flexible substrate and removing the substrate from the first organic layer.