To provide a semiconductor device capable of write operation to a selected magnetoresistive element without causing a malfunction of a non-selected magnetoresistive element and a manufacturing method of this semiconductor device. The semiconductor device includes a magnetic storage element having a magnetization free layer whose magnetization direction is made variable and formed over a lead interconnect and a digit line located below the magnetic storage element, extending in a first direction, and capable of changing the magnetization state of the magnetization free layer by the magnetic field generated. The digit line includes an interconnect body portion and a cladding layer covering therewith the bottom surface and the side surface of the interconnect body portion and opened upward. The cladding layer includes a sidewall portion covering therewith the side surface of the interconnect body portion and a bottom wall portion covering therewith the bottom surface of the interconnect body portion. The thickness of the sidewall portion is made greater than that of the bottom wall portion.