The present disclosure relates to an electronic component joining method and a joined structure. A solder layer made of a gold-tin alloy including 20 mass % or greater of tin is formed on a light-emitting element side, and a layer including gold as a main component is formed, as a joining layer for joining to the solder layer, on a submount side. The solder layer and the joining layer are heated at a temperature below the melting point of the gold-tin alloy of the solder layer to join the light-emitting element and the submount.