本文探討海南閩語的被動句式並主要探討其被動標誌。如同大部分的漢語方言，海南閩語的被動標誌有兩個，一個是從華語借字的「被∫ i」另一個是海南閩語固有的「ioh」。本文發現帶有「ioh」的被動句可以表達受事主語的意願（volition），而「被∫ i」被動句不能表達受事主語的意願。本文還討論海南閩語「ioh」的本字。陳鴻邁（1996）及錢奠香（2002）標記海南閩語被動標誌為「要」、雲惟利（2004）標記為「欲」、海南島語會話（1941）標記為「著」，本文從語音上、語意上的關聯及從近代漢語語料的佐證，都指向「著」是海南閩語被動標記「ioh」的本字。同時，本文也提供海南閩語的致使動詞（causative verb）語料，海南閩語的被動標誌與致使動詞同形，都可由「ioh」來表達。另外，本文認為海南閩語的被動標誌正在經歷的語法化，由一個動詞實詞發展為一個被動標誌。除了語法化外，海南閩語的「著」字也產生了音變：tioh＞∂ ioh＞? ioh＞ioh。

T his paper explores the Hainan Min passive construction and passive markers. As in most Chinese languages, there are two strata for Hainan Min passive markers, ioh as a native marker and ∫ i as a borrowed one. T he ioh-passives can either simply report a passive event or express the patient subject’s volition, while the ∫ i-passsives are mostly used to describe a passive event. T his paper explores the etymological origin of the word ioh. T hree candidates for its origin are examined, and the word 著 is concluded to be phonologically, semantically, and historically the optimal solution for the origin of the passive marker. In addition, it is found that Hainan Min ioh, like Taiwanese Southern Min hoo, can function as a passive marker and as a causative verb. T he paper also proposes that a sound change of the passive marker ioh occurred in Hainan Min, which was tioh＞∂ ioh＞ ? ioh＞ioh.