Abstract: An object is to provide a makeup brush bristle material and a makeup brush bristle material assembly, both made of synthetic resin, as well as a makeup brush using such bristle material or bristle material assembly, all offering good uptake and release properties with respect to powder or liquid cosmetics. As a solution, a makeup brush bristle material constituted by S-twisted or Z-twisted synthetic resin monofilaments, characterized in that the cross-section of the monofilaments in the direction orthogonal to the axis of fiber has a cocoon shape, is provided.