Provided is a light-emitting device provided with a light reflection layer which has a high light reflectivity and which is less susceptible to deterioration of the reflectivity due to corrosion, and having an improved light extraction efficiency.A light-emitting device comprising a substrate having a conductor layer formed on its surface and a light-emitting element disposed on the conductor layer, characterized in that an overcoat layer is formed between the conductor layer and the light-emitting element, and the overcoat layer is a borosilicate glass which comprises, as represented by mol % based on oxides, from 62 to 84% of SiO2, from 10 to 25% of B2O3, from 0 to 5% of Al2O3 and from 0 to 5% in total of at least one of Na2O and K2O, provided that the total content of SiO2 and Al2O3 is from 62 to 84%, and may contain from 0 to 10% of MgO and at least one of CaO, SrO and BaO in a total content of at most 5%.