This paper gives a general overview of passive construction using /thu:k/. Also, it attempts th explain nature and characteristics of Thai passive construction using /thu:k/ from a new perspective. This paper attempts to explore and answer the following questions: 1) How to analyze /thu:k/ that is used in Thai passive expression? 2) What are syntactic and symantic characteristics of passive constructions with /thu:k/? This paper has concluded that /thu:k/ is passive verb, not auxiliary verb as traditionally has been analyzed, by providing a number of evidence against the traditional view. And /thu:k/ passive construction syntactically involves a complement sentence. Symantically, it has been traditionally thought to have adversative meaning, but it has been shown that it is not restricted to adversative meaning.