A semiconductor device and method of forming the same, the semiconductor device includes a substrate, first plug, a magnetoresistive random access memory (MRAM) structure, a spacer layer, a seal layer and a first conductive pattern. The substrate has a first region and a second region, and the first plug is disposed on a dielectric layer disposed on the substrate, within the first region. The MRAM structure is disposed in the dielectric layer and electrically connected to the first plug. The spacer layer is disposed both within the first region and the second region, to cover the MRAM structure. The seal layer is disposed on the MRAM structure and the first plug, only within the first region. The first conductive pattern penetrates through the seal layer to electrically connect the MRAM structure.