Abstract: Here is disclosed a flexible plastic sheet comprising a plurality of first direction ribs (Y.sub.1, Y.sub.2 . . . ) each having opposite sides (12, 13) extending in the first direction (Y) and curved downward crossing a plurality of second direction ribs (X.sub.1, X.sub.2 . . . ) each having opposite sides (14, 15) extending in the second direction (X) and curved downward. The sheet is continuous in an area surrounded by each pair of adjacent first direction ribs and each pair of adjacent second direction ribs which cross the pair of adjacent first direction ribs. At each crossing (C.sub.1, C.sub.2, C.sub.3, C.sub.4), one of the ribs bulges upward and the opposite side edges of this rib are connected to the top of the other rib. The plastic sheet of this invention is featured by less gloss and less sticky touch, and is preferably used as a liquid-impermeable backsheet of a disposable hygienic wearable article.