A bicycle disc brake rotor including a center rotational axis is provided with an outer member including a braking portion extending in a rotation direction of the bicycle disc brake rotor and an inner member located at an inner side of the outer member in a radial direction of the bicycle disc brake rotor and coupled to the outer member. At least one of the outer member and the inner member includes a displacement reducing structure configured to reduce displacement of the braking portion in an axial direction of the bicycle disc brake rotor.