A light diffusion sheet capable of inhibiting emission of blue light, and a backlight unit for a liquid crystal display device. The light diffusion sheet includes: a transparent substrate layer; and a light diffusion layer overlaid on the front face side of the substrate layer. The light diffusion layer is a light diffusion sheet for a backlight unit of a liquid crystal display device containing a light-diffusing agent and a binder covering the light-diffusing agent, and includes a component that attenuates blue light. The blue light attenuation component is preferably a yellow fluorescent material that generates yellow light through excitation by blue light, or a light absorbing agent that absorbs blue light. The light diffusion layer preferably includes the blue light attenuation component. Preferably, the light-diffusing agent is resin beads, and the blue light attenuation component is included in the resin beads.