To provide a coolant cleaning device adopting a new system capable of most efficiently operating the coolant cleaning device equipped with a circular vortex flow coolant tank for processing chips or the like contained in the coolant.

The coolant cleaning device is equipped with stirring rods 19, 20 at at least two positions which are equipped in the coolant in the circular coolant tank 11 so as to immerse their part, and rotate along the circumference of the circular coolant tank 11, and a coolant suction pipe 31 which is equipped at the center of the circular coolant tank 11, sucks the chips or the like deposited and accumulated at the bottom center of the circular coolant tank 11 along with the coolant. The rotational motion of the stirring rods at at least two positions which are provided in the circular coolant tank 11 and rotate at 10 rpm to 25 rpm is repeated in a cycle in which continuous operation is performed for two to four minutes and afterward the operation is stopped for 0.5 to 1.5 minutes.