A polishing brush includes: a brush body that includes a cylindrical base section and linear abrasive materials extending from a bottom surface of one side of the base section along a direction of a center of an axis of the base section, and removes burrs and performs polishing on a surface of a workpiece metal by relatively moving the abrasive materials and the workpiece metal while tips of the abrasive materials come into contact with a surface of the workpiece metal; a brush guide that is coaxial with the center of the axis and is disposed on the outside of the brush body in a radial direction so that the tips of the abrasive materials protrude from an end portion; and a displacement mechanism that changes protruding lengths of the abrasive materials from the end portion.