To eliminate the necessity of taking timing for imparting brake torque into consideration and also to reduce the cost of a device by simple structure.

This is a brake-torque imparting device for rolling rolls for imparting the brake torque to a rolling roll 4 to absorb the backlash in a rotational driving force transmitting mechanism for transmitting rotational driving force to the rolling roll 4 and provided with impellers 11 which are provided in both end parts in the axial direction of the rolling roll 4 rotatably integrated with the rolling roll 4 and with which rotation resistance is generated by pushing aside cooling liquid which is supplied to the rolling roll 4.