A fluid is processed between processing surfaces capable of approaching to and separating from each other, at least one of which rotates relative to the other. A first fluid is introduced between processing surfaces, by using a micropump effect acting with a depression arranged on the processing surfaces from the center of the rotating processing surfaces. A second fluid, independent of this introduced fluid, is introduced from another fluid path that is provided with an opening leading to the processing surfaces, whereby the processing is done by mixing and stirring between the processing members.