A wavelength conversion sheet filled with a large amount of phosphor, enabling the phosphor to be easily dispersed uniformly and in a large amount near the surface of an LED element. Specifically, the sheet includes: a layer formed from a heat-curable resin composition, which contains 100 parts by mass of a resin component and 100 to 2,000 parts by mass of a particulate phosphor in which the proportion of particles having a sphericity of 0.7 to 1.0 is not less than 60% of all the particles, and which exists in a plastic solid or semisolid state in an uncured state at normal temperature, wherein the average particle diameter of the phosphor is not more than 60% of the thickness of the layer formed from the heat-curable resin composition, and the maximum particle diameter thereof is not more than 90% thereof.