Abstract: A ventilated disc unit includes inner and outer annular discs coaxially coupled to each other by rib units having bifurcated outer ends, and a rib unit comprising a radially extending straight segment extending towards an inner periphery and a pair of bifurcated segments which are arranged symmetrically with respect to the straight segment so as to open towards outer ends thereof. The straight segment is discontinuous with the bifurcated segments. A plurality of grooves are disposed extending in a radial direction on inner surfaces of the inner and outer annular discs from the inner periphery of the annular discs to the middle of the annular discs. The disc unit produces increased air flow which assures efficient cooling of the discs, particularly bifurcated point areas thereof.