POWDERY MATERIAL FEEDING DEVICE

A powdery material feeding device includes a controller B05 configured to selectively conduct constantly keeping control of constantly keeping rotational speed of a motor, current or voltage applied to the motor without any change as a manipulated variable for a predetermined period, or feedback control of repetitively obtaining a difference between a discharge flow rate of the powdery material and a target value thereof at predetermined cycles and adjusting by increasing or decreasing the manipulated variable at each of the predetermined cycles in order to reduce the difference, the controller B05 conducts the constantly keeping control immediately after a motor B022 starts, shifts to the feedback control when the difference between the discharge flow rate of the powdery material and the target value thereof has an absolute value less than a threshold after the period for the constantly keeping control elapses, and conducts constantly keeping control without shifting to the feedback control when the absolute value of the difference between the discharge flow rate of the powdery material and the target value thereof is more than the threshold after the period for the constantly keeping control elapses, and the manipulated variable during the repeated constantly keeping control is changed in accordance with the difference between the discharge flow rate of the powdery material and the target value thereof after elapse of the period for latest constantly keeping control.