Abstract: A processing operation control method controls a processing operation in which a rotary tool 1 is rotated by a rotative drive unit 51, and presses the rotating rotary tool 1 is pressed by a pressing unit 52 to force the rotating rotary tool 1 into workpieces W1 and W2. Load placed on the rotary tool 1 during the processing operation is measured, an optimum rotating speed at which the rotary tool 1 is to be rotated and/or an optimum pressure to be applied to the rotary tool 1 for processing the workpieces W1 and W2 is determined on the basis of the measured load placed on the rotary tool 1. The rotative drive unit 51 and/or the pressing unit 52 are controlled on the basis of the optimum rotating speed at which the rotary tool 1 is to be rotated and/or the optimum pressure to be applied to the rotary tool 1.