Brake disc and method of manufacturing the same

A brake disc comprising:

• a braking part having a circular plate shape having a hollow portion and a plurality of coupling portions protruding and extending from an inner diameter surface;
• and
• a hat part positioned in the hollow portion and having a plurality of insertion portions protruding laterally;
• wherein the each of the plurality of coupling portions is coupled to one of the plurality of insertion portions, and each of the coupling portions and each of the insertion portions are joined to only one of an outboard portion or an inboard portion of the braking part;
• wherein a plurality of outer coupling ends protrude and extend from an inner diameter surface of the outboard portion, and a plurality of inner coupling ends protrude and extend from an inner diameter surface of the inboard portion, and corresponds to the plurality of outer coupling ends;
• wherein a coupling portion extends and is bent from an end of each of the plurality of outer coupling ends, and the coupling portion has a coupling groove into which the insertion portion is inserted;
• and
• wherein an outer diameter of an end of the insertion portion is larger than an outer diameter of a middle of the insertion portion, and an inlet of the coupling groove is narrower than an interior of the coupling groove.