Disclosed are a method for manufacturing a half-metallic magnetic oxide and a plasma sputtering apparatus used in the method. A conductor provided with at least one hole is disposed between a metal target and a substrate holder in the plasma sputtering apparatus, thereby improving the bonding of metal ions discharged from the metal target to oxygen ions, and a magnetic field with a coercive force larger than that of a thin film to be formed on the substrate, thereby obtaining a magnetic oxide film with excellent properties. In a preferred embodiment of the present invention, a conductor-side power supply unit is connected to the conductor, thereby additionally supplying power to the conductor and generating second plasma. The plasma sputtering apparatus supplies high power so as to decompose oxygen, and discharges metal ions with different electrovalences at a precise ratio by the additional power supply, thereby being effectively used in manufacturing a half-metallic oxide at low temperatures.