Effects of the preparation condition on magnetic properties were investigated in isotropic TbCu₇-type Sm-Zr-Fe-Co-N materials made by the melt-spinning process. All the Sm-Zr-Fe-Co powders melt-spun with wheel speeds of 30-40 m/s showed a single-phase structure with crystalline TbCu₇. The grain size of the powder decreased monotonically with the increase of the wheel speed. The H_cJ, B_r and (BH) _max of the powder increased with decreasing grain size. In this study, maximum hard magnetic property was achieved in Sm _8.7 Zr _1.0 Fe _85.8 Co _4.5 N_x powder melt-spun at 40 m/s. A compression-molded bonded magnet using powder melt-spun with at a wheel speed of 40 m/s showed excellent hard magnetic properties: B_r=0.83 T, H_cJ=720.5 kA/m, (BH) _max=113.9 kJ/m ³. These results show that the TbCu₇-type Sm-Fe-N material has high performance and practicality for isotropic bonded magnets.