PURPOSE: To prevent dust, such as photoresist from being dispersed to the outside of a wafer processing cup which is used for an apparatus for treating a semiconductor wafer or the like.

CONSTITUTION: A first cup member 13 and a second cup member 14, which are placed in parallel to each other, are installed above a semiconductor wafer 2 held by a chuck 1 in such a fashion that the bottoms of the cups 13a and 14a are up in an up-side-down state and parallel to the water 2. Larger-sized opening areas 13b and 14a compared with the size of the wafer are formed in the central part of the bottoms 13a and 13b of the cup members 13 and 14 while the parts near the opening are flattened. This construction makes it possible to prevent a rear-side treating liquid from flowing to the front surface of the wafer with the first cup member and further prevent dust, such as of photoresist from being dispersed outside the cups simultaneously, thereby extending the cleaning maintenance cycle of a wafer processing device and enhancing the product quality as well.