PURPOSE: To wash filtering tubes in a metallic filtering unit with simple means.

CONSTITUTION: In an apparatus composed of a filtering vessel for filtering molten metal and the filtering unit setting the ceramic tubes in several steps at vertical direction and right and left sides in between a front side plate and a rear side plate made of silicon carbide quality plate, a partition plate 15, which can partition flow passage coming to one side of chambers 7, 6 at right and left sides in between the filtering chambers 7, 6 and a molten metal inlet hole 8, and a shut off valve 13, by which molten metal in one side of chamber 7, 6 at right or left side can be reversely flowed into the other chamber 6, 7 at between the chambers 7, 6 and a molten metal outlet hole 9, are arranged. At the time of passing through the valve 13 together with the plate 15, the chambers 7, 6 are made to parallel filtering flow passages, and at the time of fitting the valve 13 and the plate 15, the molten metal is reversely flowed from one side of the chamber 7, 6 to the other chamber 6, 7 and one side of the ceramic tube is reversely washed.