A magnetic field shielding sheet includes: a magnetic field shielding main sheet disposed on the back of the digitizer to thus prevent affecting the digitizer; and a magnetic field shielding sub-sheet laminated in a dual on at least one of four side edges of the magnetic field shielding main sheet, and to prevent affecting the digitizer by the magnesium frame inside the portable terminal, wherein the magnetic field shielding main sheet includes a shielding layer made of a plurality of pieces, a cover layer adhered to one surface of the shielding layer, and a double-sided tape adhered to the other surface of the shielding layer. A magnetic field arising from various components incorporated in a portable terminal device is shielded by the magnetic field shielding main sheet while the magnetic field shielding sub-sheet prevents a digitizer from being affected by a magnesium frame, thereby enhancing performance of the digitizer.