A semiconductor light emitting device comprising: a light emitting structure comprising a first conductive type semiconductor layer, an active layer under the first conductive type semiconductor layer, and a second conductive type semiconductor layer under the active layer; a first electrode disposed on the first conductive type semiconductor layer; a reflective electrode layer under the light emitting structure and under the second conductive type semiconductor layer; and a conductive support substrate under the reflective electrode layer, and wherein the light emitting structure comprises a second outer groove at an outer circumference of each of the first conductive type semiconductor layer, the active layer and the second conductive type semiconductor layer with a predetermined depth exposing the second conductive type semiconductor layer, such that the second conductive type semiconductor layer includes a center portion, where the second outer groove is not formed, and a circumference portion surrounding the center portion, where the second outer groove is formed, the semiconductor light emitting device further comprising an outer protection layer between the reflective electrode layer and the circumference portion of the second conductive type semiconductor layer, wherein an upper surface of the outer protection layer is in contact with a bottom surface of the second conductive type semiconductor layer, and wherein a width of the second outer groove is smaller than a width of the outer protection layer, characterized in that: a thickness of the outer protection layer ranges from 500 nm to 500 μ m, the outer protection layer comprises at least one of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN, and is doped with n-type dopants, p-type dopants or is undoped, and the reflective electrode layer is formed of a single layer or multilayer having one among Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Hf, or a combination thereof. a light emitting structure comprising a first conductive type semiconductor layer, an active layer under the first conductive type semiconductor layer, and a second conductive type semiconductor layer under the active layer; a first electrode disposed on the first conductive type semiconductor layer; a reflective electrode layer under the light emitting structure and under the second conductive type semiconductor layer; and a conductive support substrate under the reflective electrode layer, and wherein the light emitting structure comprises a second outer groove at an outer circumference of each of the first conductive type semiconductor layer, the active layer and the second conductive type semiconductor layer with a predetermined depth exposing the second conductive type semiconductor layer, such that the second conductive type semiconductor layer includes a center portion, where the second outer groove is not formed, and a circumference portion surrounding the center portion, where the second outer groove is formed, the semiconductor light emitting device further comprising an outer protection layer between the reflective electrode layer and the circumference portion of the second conductive type semiconductor layer, wherein an upper surface of the outer protection layer is in contact with a bottom surface of the second conductive type semiconductor layer, and wherein a width of the second outer groove is smaller than a width of the outer protection layer, characterized in that: a thickness of the outer protection layer ranges from 500 nm to 500 μ m, the outer protection layer comprises at least one of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, and AlInN, and is doped with n-type dopants, p-type dopants or is undoped, and the reflective electrode layer is formed of a single layer or multilayer having one among Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Hf, or a combination thereof.