To provide a polishing brush high in polishing force and suitable for polishing a hard material.

The polishing brush 10 is constituted by binding a plurality of brush bristle materials 11 containing diamond particles as abrasive grains, covering an outer peripheral part 11a thereof with a binding member 12 in order to bind up them, and holding a base part 11b of the bound brush bristle materials 11 by a brush holder 13. The brush bristle material 11 is a monofilament having a circular cross section which is made of polyester resin containing the abrasive grain which is obtained by coating a surface of the diamond particle with nickel or alloy mainly consisting of nickel.