本文主要通過對美國《外國主權豁免法》第1603 節b 款agency or instrumentality 的分析，說明瞭其含義及其與外國國家的區別，並對中文譯文提出了筆者的看法， 認為譯為「國家代理機構」更為合理。接著系統整理了美國法院在司法實踐中遇 到的層級問題、共有問題、機關條款認定這三個問題，得出美國法院目前對於層 級問題給予了明確拒絕的態度，對共有問題和機關條款的界定問題尚未確定，有 待法院在實踐中進一步確定。通過對FSIA「國家代理機構」的分析可知，若一國 的國有企業或其他實體欲在美國享有國家豁免的權利，可以證明證明其符合「機 構」條款，進而屬於FISA 定義中的外國「國家代理機構」。

Beginning with the meaning of “agency or instrumentality” in § 1603(b) of FSIA, this essay tells the difference between foreign agency or instrumentality and foreign state, and discusses the translation in Chinese. In U.S. judicial practices, the courts facing the problem of tiering, pooling and the “organ” item in § 1603(b). Not until 2003 the Supreme Court rejected tiering in Dole Food v. Patrickson and the other two problems have not been solved. We can infer from the analyses that if a foreign entity e.g. state-owned corporation wants to enjoy the qualification of subject of state immunity in the U.S., it can prove itself the “organ” of a foreign and thus fits the agency or instrumentality.