Co-Ni-Fe-N thin films were fabricated by a N₂ reactive rf magnetron sputtering method. The nitrogen partial pressure (P_N2) was varied in the range 0~10% . As P_N2 increases in this range, the saturation magnetization (B_s) linearly decreases from 19.8 kG to 14 kG and the electrical resistivity (ρ) increases from 27 to 155 µΩcm. The coercivity (H_c) exhibits the minimum value at 4% P_N2. The magnetic anisotropy fields (H_k) are in the range of 20~50 Oe. High frequency characteristics of (Co_22.2Ni_27.6Fe_50.2)_100-xN_x films are excellent in the range of 3~5% of P_N2. In particular, the effective permeability of the film fabricated at 4% P_N2 is 800, which is maintained up to 600 MHz. This film also shows Bs of 17.5 kG, H_c of 1.4 Oe, resistivity of 98 µΩcm and H_k of about 25 Oe. Also, the corrosion resistance of (Co_22.2Ni_27.6Fe_50.2)_100-xN_x films was improved with increasing N concentration.