As part of the fundamental studies on the recovery of Au by solvent extraction, the synergism of combined extractants on the extraction of An from the sulphuric acid solution containing thiourea was investigated. Extractants tested were di-(2-ethylhexyl)phosphoric acid (D2EHPA), tri-n-octylamine (TOA), tri-n-butyl phosphate (TBP), and trioctyl phosphine oxide (TOPO). Four kinds of extractant combinations, D2EHPA/TBP, D2EHPA/TOPO, TOA/I'BP, and TOAITOPO, were tested to clarify the synergism on the extraction of Au in terms of various concentration ratios, diluents, the concentration of sulphuric acid, and the concentration of thiourea.