A Sn--Ag--Cu based lead-free solder ball which does not undergo yellowing of its surface when formed into a solder bump on an electrode of an electronic part such as a BGA package. The solder ball has excellent wettability and does not form voids at the time of soldering, even when it has a minute diameter such as 0.04-0.5 mm. It has a composition comprising 1.0-4.0 mass % of Ag, 0.05-2.0 mass % of Cu, 0.0005-0.005 mass % of P, and a remainder of Sn.