To seep the inside of the corner part and the bottom of an uneven part by planting a group of fiber bundles radially so that the more the fiber bundle is located outside, the more it is inclined outward, uniformly cutting the upper end faces of the fiber bundles to the horizontal, and forming an acute part on the edge of the fiber bundle group.

A brush base plate 1 is fixed on one end of a handle, and fiber bundles 3 rich in elasticity are planted at designated spaces from the reference surface 2 of the base plate 1. The fiber bundles 3 located outside are planted to be inclined outward so that the fiber bundle 3 is radially seen from the side. The upper end faces 6 of the fiber bundle group formed by the fiber bundles 3 are cut uniformly to be horizontal. Thus, the angle between the outer edge of the fiber bundle 3 and the upper end face 6 is an acute angle ranging from 60° to 45° to form an acute part 7 at the edge of the fiber bundle group. Accordingly, sweeping for the portion hard to be coped with can be surely performed.