Sludge waste was mixed with ferro frit powder, a sintering agent, and the homogeneous and inhomogeneous distributions of the sintering agent in the sludge were compared and analyzed. In nuclear power plants containing stainless-steel disposal tanks, stainless-steel oxide-based sludge is generated from long-term exposure to radioactive fluid waste, and this sludge waste should be disposed of via solidification. By adding only 10 % ferro frit 3195 to 90 % oxide sludge waste, stable solidified sludge was made. The production processes of solidified sludge consisted of three parts: homogeneous mixing of ferro frit 3195 and sludge, compression molding of the mixed powder by hydraulic press at room temperature, and heating at 900 degrees C, where the solidified body with the homogeneous distribution of ferro frit 3195 could form stable solidified sludge. The leachability index of nonradioactive Co and the compressive strength of stable solidified sludge made by homogeneous mixing of ferro frit and oxide sludge were 16.9 f 0.0647 and 4.97 MPa, respectively.