The present invention provides a substrate structure and a method of fabricating the substrate substrure. The method includes: forming a first wiring layer on a first carrier, forming a dielectric layer on the first wiring layer, forming a second wiring layer on the dielectric layer, forming an insulating protection layer on the second wiring layer, forming a second carrier on the insulative protection layer, and remvoing the first carrier. The formation of the second carrier provides the substrate structure with adequate rigidity to avoid breakage or warpage such that the miniaturization requirement can be satisfied.