To provide a rotary roll brush having a brush material with improved cooling effect, prevented from thermal enbrittlement by guiding cooling water supplied from water discharging hole of a rotary shaft into a gutter-shaped channel spirally wound on the rotary shaft and passing water through the brush material held at the channel.

The rotary roll brush is formed by spirally winding a channel-shaped brush 1 which is formed by clamping and holding the base part of the brush material 2 by the gutter-shaped channel 4, is made to discharge the cooling water 11 discharged from water discharging holes 10 formed on the rotary shaft 7 toward the gutter-shaped channel 4 by a centrifugal force of the rotary shaft 7, and is constructed so as to guide the cooling water 11 discharged from the water discharging holes 10 formed on the rotary shaft 7 into the gutter-shaped channel 4 through water discharging holes 17 of the gutter-shaped channel 4, by opening many water discharging holes 17 penetrating through a bottom plate 5 of the gutter-shaped channel 4 along a longitudinal direction on the bottom plate of the gutter-shaped channel 4 forming the channel-shaped brush 1.