The effects of Nb addition and annealing on the magnetic properties were in vestigated for (Fe_(0.82)Ni_(0.18-x)Nb_x)_(83)Si_5B_(12) amorphous alloys which have law metalloid content. In this study, the amorphous nature of alloys prepared by single roll method was confirmed by X-ray diffraction method. Magnetic field annealing was performed at various temperatures below the crystalliztion temperature for 20 minutes in N₂gas atmosphere. With increasing Nb content, the thermal stability and both AC and DC magnetic properties were improved. Longitudinal magnetic field annealing also greatly improved the DC and 60 Hz characteristics. These improvements were attributed to the reduction of domain width by Nb addition, the induction of uniaxial magnetic anisotropy, and disappearance of Maze domains by magnetic field annealing. Transverse magnetic field annealing found to be very effective for the improvement of high frequency magnetic properties.