A slurry delivery conduit for a mixer of a gypsum board production apparatus, wherein the mixer has a mixing area for mixing of a gypsum slurry to be fed onto a continuously conveyed sheet of paper for gypsum board liner and wherein the slurry delivery conduit configures a curved or L-shaped fluid passage, which is arranged to discharge the slurry introduced from the mixing area of the mixer, onto said sheet through slurry discharge ports of the slurry delivery conduit, wherein the slurry delivery conduit comprises: a rectilinear tube segment, a branch part for branching the rectilinear tube segment, and a plurality of branch tube segments connected to the rectilinear tube segment through the branch part, wherein said rectilinear tube segment extends straightly on a downstream side in a conveying direction of said sheet to configure a rectilinear fluid passage for said slurry; wherein adjacent tube wall portions of said branch tube segments join together at said branch part to configure a transverse or horizontal cross-section in a form of V-letter, and the adjacent branch tube segments extend from the branch part on the downstream side in the conveying direction, while diverging toward the downstream side at an angle (θ2) in a range from 20 degrees to 150 degrees as seen in a plan view; and wherein said branch part splits an axial or rectilinear current of said slurry flowing out through said rectilinear tube segment and introduces branched streams (S1, S2) of the slurry into said branch tube segments respectively, and each of the branch tube segments is provided with said slurry discharge port at a terminal end part of the branch tube segment on the downstream side, so as to discharge the branched stream through the port onto said sheet, characterized in that the slurry delivery conduit further comprises a vertical tube into which the slurry is introduced from said mixing area, the rectilinear tube segment being connected to an outer circumferential surface of a lower end portion of the vertical tube through which the slurry is introduced into the rectilinear tube segment. a rectilinear tube segment, a branch part for branching the rectilinear tube segment, and a plurality of branch tube segments connected to the rectilinear tube segment through the branch part, wherein said rectilinear tube segment extends straightly on a downstream side in a conveying direction of said sheet to configure a rectilinear fluid passage for said slurry; wherein adjacent tube wall portions of said branch tube segments join together at said branch part to configure a transverse or horizontal cross-section in a form of V-letter, and the adjacent branch tube segments extend from the branch part on the downstream side in the conveying direction, while diverging toward the downstream side at an angle (θ2) in a range from 20 degrees to 150 degrees as seen in a plan view; and wherein said branch part splits an axial or rectilinear current of said slurry flowing out through said rectilinear tube segment and introduces branched streams (S1, S2) of the slurry into said branch tube segments respectively, and each of the branch tube segments is provided with said slurry discharge port at a terminal end part of the branch tube segment on the downstream side, so as to discharge the branched stream through the port onto said sheet, characterized in that the slurry delivery conduit further comprises a vertical tube into which the slurry is introduced from said mixing area, the rectilinear tube segment being connected to an outer circumferential surface of a lower end portion of the vertical tube through which the slurry is introduced into the rectilinear tube segment.