The amorphous Fe(100-x)B(x) alloys with 18 ≤ x ≤ 42 were prepared by applying a rf-sputtering technique. The chemical composition of the sputtered films was well controlled by varying the area ratio of B plate to Fe plate, which were used as a composite target. The crystallization temperature of the amorphous films linearly rises with increasing of B content up to x = 36, but falls in a composition range of 36 ≤ x ≤ 42. The amorphous Fe(100-x)B(x) films exhibited ferromagnetism in the whole compositions studied in the present work. The internal magnetic field of the amorphous films decreases with increasing of B content, since the charge transfer increases with B atom in the system Fe(100-x)B(x).