To provide a cutting water treatment apparatus, almost recovering chips in a first tank to which the used cutting water is first introduced, thereby preventing defective quality of a product due to biting of chip caused by reuse of recovered cutting water, decreasing the frequency of replacing the cutting water, and preventing the generation of malodor such as foul odor to improve the work environment.

This cutting water treatment apparatus is a treatment apparatus for used cutting water generated in cutting work of a product using a machine tool. The treatment apparatus has a filter tank formed of a plurality of sub-tanks divided by partition plates. In the first sub-tank to which the used cutting water is first introduced, the upstream side and the downstream side are parted by a partition plate shaped so that only the vicinity of the sub-tank bottom can pass water, the partition plate dividing between the downstream side of the first sub-tank and a second sub-tank to which the cutting water is next transferred is shaped so that only the cutting water near the water level can be passed, and further the partition plate dividing between the second sub-tank and a third sub-tank to which the cutting water is subsequently transferred is shaped so that a hole for passing the cutting water is provided in a part substantially near the half of depth of water.