A fabricating method of a flexible display device includes the steps of providing an adhesive layer including a first adhesive material on a first surface of a support film, a second adhesive material on a second surface of the support film such that an adhesive strength of the second adhesive material is lower than an adhesive strength of the first adhesive material, and a third adhesive material encompassing an edge of the second adhesive material such that an adhesive strength of the third adhesive material is higher than the adhesive strength of the second adhesive material; a first passivation film adhered to the first surface of the support film with the first adhesive material therebetween; and a second passivation film adhered to the second surface of the support film with the second adhesive material and the third adhesive material therebetween; peeling the first passivation film from the adhesive layer; adhering a rigid substrate to the first adhesive material; peeling the second passivation film from the adhesive layer; and adhering a flexible substrate onto the second and third adhesive materials.