Mechanical grinding(MG) in Ar and mechanical alloying(MA) in NH₃ have been applied to prepare Sm₂Fe₁₇Nx permanent magnet, where the three diffrent kinds of alloy powders, i.e., Sm₂Fe₁₇, Sm₂Fe₁₇C and Sm₂Fe₁₇C₂ were used as the starting materials. Though Sm₂Fe₁₇ and Sm₂Fe₁₇C specimens obtained by MG or MA were recognized to consist of α-Fe and Sm-Fe amorphous phase, Sm₂Fe₁₇C₂ specimen obtained by MG or MA process was confirmed to consist of only Sm-Fe amorphous phase. The fine grain particles under a single domain size( ?? 260nm) were obtained both by MG and MA, where the powder obtained by MA in NH3 was finer than that obtained by MG in Ar. Nitrogen content of the powder obtained by MA in NH₃, increased as MA time passed. On the contrary, hydrogen content once increased at the first stage of MA, and after that decreased with the increase of MA time.