A substrate structure applied in flexible electrical devices is provided. The substrate structure includes a carrier, a first material layer overlying the carrier with a first area, a second material layer overlying the first material layer and the carrier with a second area, and a flexible substrate overlying the second material layer, the first material layer and the carrier with a third area, wherein the second area is larger than or equal to the first area, the third area is larger than the second area, and the flexible substrate has a greater adhesion force than that of the first material layer to the carrier. The invention also provides a method for fabricating the substrate structure.