A high frequency magnetic thin film characterized by comprising a first layer made of a T-L composition (here, T is Fe or FeCo, and L is one or more of C, B, and N) and a second layer comprising a Co-based amorphous alloy arranged on either of the surfaces of the first layer. The high frequency magnetic thin film is a multilayer film of a plurality of the first layers and a plurality of the second layers or desirably is a multilayer film of alternately laminated first and second layers. The high frequency magnetic thin film of the present invention exhibits the properties such that the real part (.mu.') of the complex permeability is 400 or more at 1 GHz, a quality factor Q (Q=.mu.'/.mu.'') is 4 or more, and a saturation magnetization is 14 kG (1.4 T) or more.