To provide a relatively inexpensive soft magnetic amorphous alloy which has high amorphous-forming ability, also has relatively high saturated magnetic flux density and further uses little amount of expensive elements.

The soft magnetic amorphous alloy has alloy composition other than inevitable impurities, expressed by compositional formula: (Fe1-aMa)100-w-x-y-zSiwBxCyLz, wherein among the constituent elements in the compositional formula, M is one or more kinds of elements selected from among Co and Ni; and L denotes one or more kinds of elements selected from among Al, Cr and Mo, and wherein compositional ratios satisfy 0a0.3, 4 atomic%w10 atomic%, 1 atomic%y7 atomic% and 0.3 atomic%z5 atomic%, and satisfies all the conditions in which the temperature range of the region of a supercooled liquid is 20C and saturated magnetic flux density is 1.2T.