The present invention provides a flexible display device manufacturing method and a flexible display device. The flexible display device manufacturing method of the present invention protects a folding region by adhering a protective tape on an entire surface of the folding region of a flexible display panel. Compared to the prior art of coating an ultraviolet glue on the folding region to form a protective layer, the method can effectively improve flatness of the surface of the protective layer in the folding region to advantage folding and shaping of the folding region, lower a risk of circuit wires in the folding region broken during the folding process, further reduce a defect rate of the products during the folding process and enhance quality of the products.