A lighting apparatus includes a housing, a light emitting module disposed on an open region at one side of the housing, and a heat sink unit placed within the housing to absorb and discharge heat from the light emitting module. The light emitting module includes a heat sink base on which a semiconductor optical device is mounted. The heat sink unit includes at least one main heat pipe having one side adjoining the heat sink base and a heat sink block adjoining the other side of the main heat pipe to cooperate with the main heat pipe.