Abstract: In accordance with one aspect of the present invention, there is provided a high-manganese steel brake disk comprising: a first disk member that includes a first disk main body, a plurality of first concave-convex portions arranged on the first disk main body so as to be radially spaced apart from each other, and a first insertion portion formed between the first concave-convex portions adjacent to each other; and a second disk member that includes a second disk main body, a plurality of second concave-convex portions arranged on the second disk main body so as to be radially spaced apart from each other, and a second insertion portion formed between the second concave-convex portions adjacent to each other.