PURPOSE: To improve the chatter cuttability of metallic fiber and to permit the continuous working for a long period of time by specifying the contents of C, P, S, Ni and Cr and setting the balancing ratio of Ni equivalence to Cr equivalence into the specific range.

CONSTITUTION: The contents of the elements in a stainless steel are regulated in such a manner that ≤0.07% C, ≤0.04% P, ≤0.04% S, ≥10% Ni and ≥17% Cr are at least incorporated and is required, 2W4% Cu is incorporated thereto. The balancing ratio of the Ni equivalence defined by the formula I to the Cr equivalence defined by the formula II (Ni equivalence/1.07×Cr equivalence-9) is set in such a manner that the range of 1W3 is satisfied. The number of troubles such as chipping of a tool attendant on cutting is reduced by the stainless steel having said compsn. The strength of the metallic fiber subjected to chatter cutting is furthermore made sufficient.