PROBLEM TO BE SOLVED: To provide: an optical semiconductor light-emitting device which enables the reduction in a blue light component emitted together with white light, and enables the increase in brightness; a luminaire including such an optical semiconductor light-emitting device; and a display device.SOLUTION: An optical semiconductor light-emitting device operable to emit white light comprises: an optical semiconductor light-emitting element; a light conversion layer including phosphor particles; and a light scattering layer provided on the light conversion layer and including an object into which a light scattering composition including light scattering particles and a binder is cured. The light scattering particles are surface-modified by a surface-modifying material having at least one functional group selected from an alkenyl group, a H-Si group and an alkoxy group, and made of a material absorbing no light in an optical semiconductor emission wavelength region, and have an average primary particle d
