There is provided a brushless motor and a driving control device therefor both of which can restrain the occurrence of current variations, torque variations and noise in the brushless motor, thereby constructing an electrically-operated power steering system of low noise and good steering feeling. In the driving control device for the brushless motor having a current variation rate control part which controls a current variation rate during commutation, and having plural excitation phases, the current variation rate control part terminates commutation transient time which is the time for which phase currents are in a transient state during a commutation operation, within ½ of commutation interval time which is the time required from the starting time of a certain commutation until the starting time of the next commutation.