A highly-efficient semiconductor light emitting diode with improved light extraction efficiency comprising at least a substrate having a plurality of crystal planes, a first conductivity-type barrier layer, an active layer serving as a light emitting layer and a second conductivity-type barrier layer stacked on the substrate. The semiconductor light emitting diode comprises a ridge structure configured from one flat surface and at least two inclining surfaces in the in-plane direction. The width (W) of the flat surface of the ridge structure is 2λ (λ: light emission wavelength) or less. The active layer is positioned in the laminating direction so that the shortest length (L) between two points is λ (light emission wavelength) or less, wherewith the first point is the shortest point where the light emitted from the center (C) of the active layer begins total internal reflection at the interface between the inclining surfaces of the ridge structure and air, and the second point is a point where the flat surface begins.