The silver-gold alloy bonding wire of the present invention includes an alloy composed of not lower than 10% and not higher than 30% of gold (Au) and not lower than 30 ppm and not higher than 90 ppm of calcium (Ca) with the remainder of silver (Ag) at purity relative to a metallic element except for elements Au and Ca of 99.99% or higher, in mass percentage; a layer enriched with oxygen (O) and calcium (Ca) formed as a surface layer on the surface of the alloy; and a gold-enriched layer formed immediately below the surface layer.