The present invention relates to lean duplex stainless steel having a dual-phase structure of an austenite phase and a ferrite phase, and a method for producing the lean duplex stainless steel, the lean duplex stainless steel according to one embodiment of the present invention, as a ferrite-austenite stainless steel, having the preferred stacking fault energy (SFE) value of the austenite phase, expressed by the formula 2 below, of 19-37 and critical strain value range, within which the strain-induced martensite phases occurs, of 0.1-0.25. SFE = 25.7 + 1.59 × Ni / K Ni − K Ni × V γ + V γ + 0.795 × Cu / K Cu − K Cu × V γ + V γ − 0.85 × Cr / K Cr − K Cr × V γ + V γ + 0.001 × Cr / K Cr − K Cr + V γ + V γ 2 + 38.2 × N / K N − K N × V γ + V γ 0.5 − 2.8 × Si / K Si − K Si × V γ + V γ − 1.34 × Mn / K Mn − K Mn + V γ + V γ + 0.06 × Mn / K Mn − K Mn × V γ + V γ 2 where Ni, Cu, Cr, N, Si and Mn indicate the overall content (wt.%) of the respective constituent element, and K(x) is the distribution index of respective constituent element (x) and is expressed by the formula 3 below, and V(γ) is the component ratio of austenite (in the 0.45-0.75 range). K x = amount of element x in ferrite phase / amount of element x in austenite phase