We have produced Fex‐Ni80−x‐B15‐Si5(x=20, 40, and 75) and permalloy thin films on a silicon substrate using ion‐beam sputtering technique. Four‐point probe measurement indicated that quarternary films had 3–4 times higher resistivity than permalloy films, and this ratio was not changed after thermal annealing. The values of saturation magnetization were determined to be 5–13 kG depending on Fe concentration. The anisotropy fields of these films were in the ranges of 2–15 Oe after deposition, however, these values were reduced by more than 50% after annealing with field. The lowest value of the anisotropy field was 1.3 Oe for the permalloy film after thermal annealing without field.