A light-emitting diode device includes a light-emitting diode, a lens cap made of synthetic resin, for covering the light-emitting surface of the light-emitting diode means, and a refractive layer formed between the light-emitting surface and the lens cap, the refractive layer having a composition, such as an air layer, with a refractive index different from the refractive index of said synthetic resin. In this arrangement the relationship between the light intensity and directional angles is shown by characteristics in which the light intensity is maximum in the center of the directional angles, and is relatively flat in the form of a sinusoid in the wide range of the directional angles. Therefore, even when the characteristics of each light-emitting diode is not verified, a predetermined light-signal transmission range is readily obtained without being affected by a scatter in the characteristics.