A CoNiFe film with saturation magnetic flux density (B-s) greater than 2.0 tesla (T) has been prepared for the first time as a soft magnetic film; the coercivity (H-c) of the film is less than 160 A/m (2.0 Oe). This success was achieved by formulating a new plating bath and operating conditions to form fine grains. The film has a low H-c of less than 160 A/m, a low saturation magnetostriction (lambda(s)) of approximately 10(-6), and a high B-s of 2.0-2.1 T. The present invention is expected to contribute to accelerating the development of not only the technology of high-density magnetic recording but also the field of magnetic materials in general.