Abstract: A surface treatment device capable of carrying out the surface treatment such as washing or etching of plate-like articles such as semiconductor wafers maintaining high degree of reliability, wherein a surface treating liquid is introduced into a ring-like or a conduit-like treating vessel. The plate-like articles to be treated are moved by a conveyor on a conveyor path having a surface in parallel with the surfaces of the plate-like articles against the stream of the treating liquid in a piece-by-piece manner, so that the surfaces of the plate-like articles are treated, whereby the surfaces of the semiconductor wafers can be desirably treated prior to manufacturing the semiconductor products.