Sr-La-M ferrite fine particles were prepared by mechanical compounding using the planetary ball-mill and subsequent heat treatment. This experiment was carried out to investigate the effect of La₂O₃ additive on the magnetic properties of Sr-M ferrite fine particles. The optimum condition of making Sr-La-M ferrite fine particles and some properties of typical specimens are as follows; chemical composition: SrO.5.75Fe₂O₃; additive: 1.0wt%aLa₂O₃; planetary ball-mill condition: 300rpm×1h; heating condition: 1050°C×1h in air; magnetic and lattice constant are σ_s=88.3×10^-6Wb⋅m/kg, H_CJ=476kA/m, Tc=459°C and lattice constant a=5.880×10^-10m, c=23.01×10^-10m.