A high manganese austenitic steel having high yield strength according to one aspect of the present invention, comprises: by wt%, 0.2% to 0.5% of C, 20% to 28% of Mn, 0.05% to 0.5% of Si, 0.03% or less of P, 0.005% or less of S, 0.005% to 0.05% of Al, and the remainder being Fe and other unavoidable impurities; and 95 area% or more of austenite as a microstructure, wherein the grain boundary fraction in crystal grains of the microstructure may be 7 area% or more.