To provide a manufacturing method for an optical sheet by which a first optical sheet having a variety of surface shapes and optical characteristics can be manufactured from one shaping roll, because reduction in the cost and thickness is requested for a display device using a directly-below type light source unit.

In the method for manufacturing a first optical sheet, an optical sheet base material formed with cylindrical optical elements on the light-emitting surface with a pitch P of 200 μm or less, a height H of 200 μm or less, and an H/P value of 0.1 to 0.9 is stretched under the following condition: 100×(|A-B|)/((A+B)/2)≤10, wherein A is the brightness at a point directly above cold-cathode tube lamps on the optical sheet closest to a front panel, and B is the brightness at a center point of adjacent cold-cathode tube lamps on the optical sheet, when 2d<W is conditioned, wherein an interval between multiple cold-cathode tube lamps as a linear light source is W, and a distance between the optical sheet placed on the light source and the light source is d.