The invention relates to a washing processing apparatus and a control method thereof. The washing processing apparatus comprises a washing groove which contains washing bags for rotation and a motor enabling the washing groove to rotate. The control method comprises steps including enabling the motor to rotate under a no-load state or specific load in a calibration mode; storing at least one value among a washing bags reference value, an offset reference value, and a speed rise/decrease gradient reference value, based on flowing current in the motor or motor speed; enabling the motor to rotate in a running mode; determining at least one among washing bags amount, offset, speed rise/decrease gradient based on the stored reference value and flowing current in the motor or motor speed. Accordingly, driving efficiency is improved.