A semiconductor light emitting device, includes an active layer radiating a light having a predetermined wavelength; a first semiconductor layer of a first conductivity type, provided on the active layer. A semiconductor substrate has a first principal surface in contact with the active layer, a second principal surface facing the first principal surface, and side surfaces connected to the second principal surface. Each of the side surfaces has a bevel angle in a range from about 45 degrees to less than 90 degrees with respect to the second principal surface. A second semiconductor layer of a second conductivity type is provided under the active layer. A first electrode is provided under the second semiconductor layer. A distance between the active layer and the first electrode depends on the wavelength and a refractive index of the second semiconductor layer.