PURPOSE: To obtain a Fe3B type R-Fe-B system magnet enhancing iHc and (BH) max and having optimum residual magnetic flux density Br by a method wherein an alloy hot melt of a specific composition is made an amorphous organization by a quenching method and further heat-treated to obtain an ultra- fine crystal aggregate.

CONSTITUTION: In an alloy hot melt that a composition range of Fe100-x-y-zCoxBy(R1-aDya)Pbw (R is Pr or Nd) satisfies 0.05≤x≤15at%, 16≤y≤22at%, 3≤z≤5.5at%, 0.02≤a≤0.9 and 0.1≤w≤3at%, it is made an amorphous organization by a quenching method, and further heat-treated. Thus, a mean crystal particle size becomes an ultra-fine cyrstal aggreate of 0.01 to 0.1μm, and a quantity ratio of Nd2Fe14B type crystal configuration increases in addition to a Fe3B type compound phase of a main phase to form a permanent magnet thin band. This can be pulverized to obtain magnetic characteristic of iHc≥4kOe, Br≥7kG and (BH)max≥8MGOe, and also obtain the optimum magnetic alloy powder for a bond magnet having residual magnetic flux density of 5kG or more.