Austenitic stainless steel sheet and manufacturing method thereof

By mass%, C + N: 0.03~0.20%, Si: 0.1~1.5%, Mn: 0.10~1.5%, Cr: 15.0~22.0%, Ni: 4.5~10.0%, Cu: 0.10~2.0%, Mo: 0.1~2.0%, Nb: 0.02~0.50%, a remainder of Fe and impurities, the average grain size of 5.0μm or less, non-recrystallized portion remaining rate of 3.0% or less, an average aspect ratio of crystal grains is 1.2 or less, etching, austenitic suitable for precision processing such as laser processing stainless steel plate.