A magnetic electronic device comprises a substrate, a buffer layer, a first CoFeB layer, a first metal oxidation layer and a capping layer. The buffer layer is disposed above the substrate. The first CoFeB layer is disposed above the buffer layer. The first metal oxidation layer is disposed above the first CoFeB layer. The capping layer is disposed above the first metal oxidation layer and covers the first metal oxidation layer. A manufacturing method of the magnetic electronic device is also disclosed.