Disclosed herewith is an extracting structure for incorporating a substance contained in a first liquid into a second liquid. The extracting structure comprises: a channel for allowing the first liquid and the second liquid to flow therein in a form of a layered flow in which first laminar flows of the first liquid and second laminar flows of the second liquid alternately come in contact with each other, wherein the substance in the first laminar flow of the first liquid moves to the second laminar flow of the second liquid through the boundaries between the first laminar flows and the second laminar flows; and a separating section, connected to a lower stream side of the channel, for separating the second liquid from the first liquid. Further, disclosed also herewith is a separating structure for separating a second liquid from the mixture of a first liquid and the second liquid.