An alloying-element additive for adding an alloy element to a copper melt formed by melting a base material including a copper in manufacturing a copper alloy. The alloying-element additive includes a wire-shaped or plate-shaped core including an alloy element, and an outer layer material including a copper and covering the core. A weight ratio of the copper in the outer layer material and the alloy element in the core is in a range of weight ratio where the alloying-element additive has a liquid phase in a temperature range of not more than a melting point of the copper in a copper-alloy element phase diagram.
