The invention provides a copper ball, and the copper ball is small in alpha ray amount and high in sphericity degree even when a certain number of impurity elements are included besides Cu. To restrain soft errors and reduce poor connection, the content of U and the content of Th are set to be 5 ppb or below, the purity is set to be 99.995% or below, and the alpha ray amount is 0.0200 cph/cm<2> orbelow. In addition, unexpectedly, the sphericity degree of the copper ball is improved by setting the purity to be 99.995% or below.