PURPOSE: To obtain a soft magnetic thin film, which is low in saturation magnetic flux density and is superior in heat resistance, by a method wherein the soft magnetic thin film has a composition, which is shown by CoxMyCz, where M is a specified element, and x, y and z are proportions.

CONSTITUTION: A soft magnetic thin film has a composition, which is shown by CoxMyCz where M is one kind of an element or more of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W and Y, and x, y and z (an atomic %) satisfy 50≤x≤82, 18≤y≤30, 0.1≤z≤20 and x+y+z=100. The film has a saturation magnetic flux density Bs of 0.45 T or lower. A magnetic head is formed using this soft magnetic thin film. Thereby, the soft magnetic thin film, which has the low Bs and is superior in heat resistance, can be obtained and if this soft magnetic thin film is used, a close contact glass, which is good in environmental resistance and is high in mechanical strength, can be used at the time of manufacture of the magnetic head and the magnetic head, which is highly reliable and has a high yield of manufacture, can be obtained.