The results of high-accuracy magnetic measurements on SUS 316LN austenitic stainless steel compressively deformed at room temperature (RT) are reported here. Even after the mild deformation of similar to 25% true strain (epsilon(t) ), the ferromagnetic phase (alpha'-martensite) could be clearly observed which increased sharply on further deformation. The amount of alpha' was very small (0.18 vol% at epsilon(t) approximate to 60%) when compared to the reported data for other grades of austenitic steels such as 304, 304L, 316, and 316L. The strain-induced alpha'-martensite is further studied by magnetic hysteresis loops. The coercivity (H-C) and remanence (M-r) were analyzed by subtracting the paramagnetic contribution of the bulk austenite structure. While H-C was found to decrease with alpha', M-r remained the same (similar to 67 emu/g) when normalized to the volume fraction of alpha'. The decreasing H-C with increasing alpha' and/or epsilon(t) is presumed to be due to the domain wall pinning at the grain boundaries when the cluster size exceeds the domain wall width.