This 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. The 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. Three 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.