Abstract: A linear or disk steel brush material for a rotary brush in which the root portions of a large number of steel brush wires are inserted and fixed into a linear or ring-like steel channel having a U-shaped cross section and an opening directed to an outer peripheral side, wherein the root portions of the steel brush wires are fixed by synthetic resin to obtain a solid portion, the solid portion is fitted into the steel channel and is then latched and fixed to a latching section projected inward from the steel channel wall, and both opening edge portions of the steel channel are curved outward.