To provide a lens array sheet which allows effective use of light, and can display a video of a high contrast, is high in accuracy, and facilitates production, and to provide a panel light source device, a back projection type display device, and a method for manufacturing the lens array sheet.

Light shielding patterns 142 having apertures 142 are formed on one surface of a base material layer 144. An acrylic UV curing type resin 145 is applied on the other surface of the base material layer 144 and is irradiated with UV rays from the side formed with the light shielding patterns 142, and the unexposed portions are removed by performing development processing and thereby the lens array sheet 14 having unit lenses 141 is manufactured.