The present invention provides a semiconductor light emitting device comprising a light intensity difference reducing layer provided between an ultraviolet semiconductor light emitting element and a wavelength converting material layer, and a backlight and a display device comprising the semiconductor light emitting device. The semiconductor light emitting device is an LED light emitting device which has improved uniformity of emitted light and reduced non-uniformity of brightness and chromaticity of emitted light. The light emitting device according to the present invention is particularly suitable for use in various display devices, preferably, for example, in display devices in equipment where a reduction in size, a reduction in weight, a reduction in thickness, electric power saving, high brightness, and excellent color rendering properties are particularly required, for example, cellular phones, personal digital assistants, electronic dictionaries, digital cameras, computers, liquid crystal televisions (TVs), and peripheral devices of these devices.