Provided is a prism sheet which has high effects of suppressing Moiré fringes, high front luminance and reduced number of components when it is used as a prism sheet for a backlight unit for a liquid crystal display device. The prism sheet has a prism row having ridges formed in parallel to each other at equivalent intervals on one surface and a light diffusion layer containing porous particles on the other surface. The prism sheet preferably has the prism row on one surface and the light diffusion layer on the other surface by having a light-transmissive substrate in between.