A high-performance spin filter tunnel junction composed of an epitaxial oxide heterostructure is reported. By independently controlling the magnetic orientations of ferromagnetic tunnel barrier and electrode layers, a tunnel magnetoresistance ratio exceeding 120% is obtained purely by the spin filtering effect. A newly introduced spin filter material, Pr0.8Ca0.2Mn1-yCoyO3, is shown to be useful for building novel multibarrier spintronic tunnel devices due to its composition-controlled magnetic hardness.