According to one embodiment, a semiconductor light emitting device includes a structure, a first electrode layer, and a second electrode layer. The structure includes a first semiconductor layer, a second semiconductor layer and a light emitting layer provided between the first semiconductor layer and the second semiconductor layer. The first electrode layer is provided on the first semiconductor layer side of the structure. The first electrode layer is made of metal and contains a portion contacting the first semiconductor layer. The second electrode layer is provided on the second semiconductor layer side of the structure. The second electrode layer has a metal portion with a thickness of not less than 10 nanometers and not more than 50 nanometers, and a plurality of openings piercing the metal portion, each of the openings having an equivalent circle diameter of not less than 10 nanometers and not more than 5 micrometers.