An Fe-based soft magnetic alloy is provided. The Fe-based soft magnetic alloy can be represented by empirical formula FeaBbCcCud, and in the empirical formula, a, b, c and d are atomic percent (at %) of the corresponding element and are respectively 78.5≤a≤86, 13.5≤b+c≤21 and 0.5≤d≤1.5. The alloy has a high saturated magnetic flux density, excellent high frequency characteristics and low coercivity, and thus greatly facilitates the development of use as high performance/high efficiency small/lightweight parts. Since manufacturing costs are very low and the components contained in an alloy are easily controlled in an alloy manufacturing process, thereby enabling mass production of the alloy, the present invention can be widely applied as magnetic parts of electric and electronic devices such as a high power laser, a high frequency power supply, a high-speed pulse generator, an SMPS, a high-pass filter, a low-loss high frequency transformer, a fast switch and wireless charging.