A semiconductor light emitting device including: a transparent substrate; an electron injection layer which is formed on the transparent substrate; an active layer which is formed on a first region of the electron injection layer; a hole injection layer which is formed on the active layer; a first electrode structure which is formed on the hole injection layer and concurrently provides a high reflectivity and a low contact resistance; a second electrode structure which is formed on a second region of the electron injection layer; and a circuit substrate which is electrically connected with the first and second electrode structures, the first electrode structure includes: a contact metal structure which has any one selected from the group consisting of nickel, palladium, platinum and ITO (Indium Tin Oxide) that have low contact resistance; and a reflective layer which has aluminum or silver.