In order to selectively extract copper and/or lead from an acidic solution containing high concentrations of manganese, etc., the valuable-metal extracting agent of the present invention is expressed by general formula (1). In the formula, R1 and R2 each represent the same or different alkyl groups, R3 represents a hydrogen atom or an alkyl group, and R4 represents a hydrogen atom or a given group, other than an amino group, that bonds with an α carbon as an amino acid. In general formula (1), the inclusion of a glycine unit, a histidine unit, a lysine unit, an asparagine acid unit, or a normal methylglycine unit is preferred. When using the extracting agent to extract copper/and lead, it is preferable that the pH of the acidic solution be adjusted to 1.0-5.5 inclusive.