To provide a mixing confluence pipe which mixes two kinds of fluid with different temperature and concentration in a short divided area.

Plural partition plates 6a-6c are arranged at an interval in the confluence aperture 5 of one of conduits 2 on the upstream side at the confluence part of the conduits, and plural partition plates 8a-8c are arranged at an interval in the confluence aperture 7 of the other conduit 4. If fluids from the conduit 2 and the conduit 4 flow through the confluence part, the fluids are allowed to flow through the layers of a sandwich structure arranged alternately by the partition plates 6a-6c, 8a-8c and consequently, numerous fluid interfaces are formed. In addition, a guide vane is formed for the fluid flowing through the other conduit 4 so that the fluid veers its direction at 90° to flow smoothly.