A method for producing an organic compound by mixing and reacting together two or more fluids, at least one of which contains a reactant, and at least one of the other fluids contains an organic compound, using an apparatus comprising: a fluid pressure imparting mechanism for imparting a predetermined pressure to a first fluid to be processed, at least a first processing member and a second processing member, the second processing member relatively approaching and separating from the first processing member, a rotation drive mechanism configured to cause relative rotation between the first processing member and the second processing member, a surface-approaching pressure-imparting mechanism acting on the second processing member to force it towards the first processing member; wherein a first processing surface on the first processing member and a second processing surface on the second processing member are disposed facing each other; each of the processing surfaces (1, 2) constitutes part of a sealed flow path through which the first fluid under the predetermined pressure is passed; of the first and second processing members, at least the second processing member is provided with a pressure-receiving surface constituting part of the sealed flow path, and at least part of the pressure-receiving surface is comprised of the second processing surface; the pressure-receiving surface receives pressure applied to the first fluid by the fluid pressure imparting mechanism thereby generating a force in the direction of separating the second processing surface from the first processing surface; and wherein the first fluid under the predetermined pressure is passed between the first and second processing surfaces to form a fluid film of predetermined thickness by the balance between the pressures imparted by the surface-approaching pressure-imparting mechanism and the forces acting to separate the processing surfaces (1, 2); another introduction path independent of the flow path through which the first fluid is passed, and at least one opening leading to the separate introduction path and being arranged in at least either the first processing surface or the second processing surface; the method comprising sending the at least one second fluid to be processed through the separate introduction path and introducing it between the first and second processing surfaces, while controlling the separation of the processing surfaces with the balance between the opposed pressures as aforesaid, whereby the reactant contained in at least one of the first and second fluids, and the other of the first and second fluids, are reacted together by mixing them under uniform stirring in the fluid film. a fluid pressure imparting mechanism for imparting a predetermined pressure to a first fluid to be processed, at least a first processing member and a second processing member, the second processing member relatively approaching and separating from the first processing member, a rotation drive mechanism configured to cause relative rotation between the first processing member and the second processing member, a surface-approaching pressure-imparting mechanism acting on the second processing member to force it towards the first processing member; wherein a first processing surface on the first processing member and a second processing surface on the second processing member are disposed facing each other; each of the processing surfaces (1, 2) constitutes part of a sealed flow path through which the first fluid under the predetermined pressure is passed; of the first and second processing members, at least the second processing member is provided with a pressure-receiving surface constituting part of the sealed flow path, and at least part of the pressure-receiving surface is comprised of the second processing surface; the pressure-receiving surface receives pressure applied to the first fluid by the fluid pressure imparting mechanism thereby generating a force in the direction of separating the second processing surface from the first processing surface; and wherein the first fluid under the predetermined pressure is passed between the first and second processing surfaces to form a fluid film of predetermined thickness by the balance between the pressures imparted by the surface-approaching pressure-imparting mechanism and the forces acting to separate the processing surfaces (1, 2); another introduction path independent of the flow path through which the first fluid is passed, and at least one opening leading to the separate introduction path and being arranged in at least either the first processing surface or the second processing surface; the method comprising sending the at least one second fluid to be processed through the separate introduction path and introducing it between the first and second processing surfaces, while controlling the separation of the processing surfaces with the balance between the opposed pressures as aforesaid, whereby the reactant contained in at least one of the first and second fluids, and the other of the first and second fluids, are reacted together by mixing them under uniform stirring in the fluid film.