An object of the present invention is to provide a headbox for a paper machine in which correction of the fiber orientation of paper is possible over the entire width of the C/D direction, regardless of the slice width, and in which the fiber orientation in the direction of paper thickness can be corrected over the entire thickness of the paper. A headbox (1) for a paper machine according to claim (1) of the present invention discharges paper raw material onto a wire as a raw material jet gj from a slice (5) which is supplied with the paper raw material, and comprises orientation correcting means (h3) for correcting the pulp fiber orientation by supplying paper raw material, which is extracted from a taper header (2) in which paper raw material for a main flow is stored, or from a correction-only taper header (2s) in which paper raw material for correcting the pulp fiber orientation is stored, as a correction flow to a single location in a central portion of the slice (5) via at least one flow control valve (b3).