<p>A headbox in a paper machine is improved in that there are provided a first flow path having a uniform cross-section in the widthwise direction for causing separation in a flow therethrough to give turbulence to the flow and thereby stir a raw paper liquid, and a second flow path having a uniform crosssection in the widthwise direction and disposed contiguously to and downstream of the first flow path, whose longitudinal cross-sectional area is smoothly decreased and increased to repeatedly subject the raw paper liquid to acceleration and deceleration without giving turbulence to the flow.</p>
