Disclosed is a brake disc rotor comprising a first disc plate, a second disc plate facing the first disc plate, a plurality of fins arranged in the radial direction of the brake disc rotor between the first and second disc plates, and a plurality of ventilation holes each of which is positioned between neighboring fins of the plurality of fins and communicates a space on the inner circumferential side and a space on the outer circumferential side in the radial direction of the brake disc rotor. The plurality of fins have a plurality of sets each including two long fins and two short fins, one of the two long fins has an expanded part which is expanded in its width direction, the long fins and the short fins are alternately arranged in the circumferential direction of the brake disc rotor in each of the plurality of sets, and the plurality of sets are arranged at equal intervals in the circumferential direction of the brake disc rotor.