An optical functional sheet characterized in that, at least within the sheet, a light diffusing phase and a transparent phase each extend along a direction perpendicular to the surface of the sheet and are alternately arranged along the sheet surface direction. The optical functional sheet has a smooth surface that can be surface-treated or laminated with another functional sheet and is provided with a light collecting effect due to the internal arrangements thereof that is capable of collecting both light diverging transversely and light diverging longitudinally using a single sheet. Thus, the sheet can be useful for applications such as the backlight for liquid crystal displays.