To obtain a brake rotor with a structure capable of restraining a rotor vibration and its manufacturing method.

For a brake rotor 10 which forms ventilation flues 16 inside of a rotor radially, the rotor is formed by a light metal or a metal based compound material 14A, and also a rotor main body and the metal based compound material with different specific gravity are arranged in balanced in a part of a ventilation flue bulkhead in several ventilation flue bulkheads arranged at regular interval positions along circumference direction. This can be produced by attaching a filling foam consisting of a reinforcement material in permeable holes placed at regular interval positions along circumference direction formed in a core for forming of the ventilation flue, and by metal casting through the core or by producing a rotor prefoam through the core, and by impregnating the metal base into this rotor prefoam.