To improve polishing performance by suppressing the decrease of the concentration of abrasive fluid while keeping the merits of an inward cylindrical brush.

The inward cylindrical brush 100 comprises a spiral brush 110 formed by spirally rounding a straight channel brush. The spiral brush is supported by supporting posts 120a to 120d such that required spaces are formed between neighboring implanted base portions 112. The spiral spaces between the neighboring implanted base portions are used as overflow openings H for abrasive fluid. The abrasive fluid is moved in the radial direction by a centrifugal force when the cylindrical brush 100 rotates. The abrasive fluid moved to the roots of bristles 111 of the brush flows outward passing the overflow openings H between the implanted base portions. Therefore, the abrasive contained in the abrasive fluid hardly jams between the bristles of the brush, and the decrease of the concentration of the polishing fluid can be suppressed.