A semiconductor light-emitting device includes a light-emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer which are sequentially stacked, a first insulating layer on the second semiconductor layer with a plurality of first openings having first widths and a plurality of second openings having second widths different from the first widths, a first electrode electrically connected to the first semiconductor layer through the first openings, a first sub-electrode layer between the second semiconductor layer and the first insulating layer, the first sub-electrode layer being exposed through the second openings, and a second sub-electrode layer on the first insulating layer, the second sub-electrode layer being connected to the first sub-electrode layer through the second openings, wherein a first distance between the first openings closest to each other is different from a second distance between the second openings closest to each other.