In this thesis, unbounded dependency constructions in Korean will be discussed within the Head-driven Phrase Structure Grammar framework English unbounded dependency constructions, that is, relative clauses, and topic clauses will be compared to Korean counterparts. Korean wh-interrogatives are not investigated as they are not syntactic dependency constructions we have adopted in this thesis. The wh-words and the constituents in question occupy the same places, that is, whwords are in situ. There is some kind of dependencies between wh-elements and the interrogative suffixes. This is a semantic dependency between wh-elements and its scope. One might assume topic clauses are unbounded dependencies but they are not in three reasons. First, the LOCAL value of the missing constituent is not identical to that of the topic. Second, topic clauses with no gap exist. Third, a gap can appear without topic. Topic clauses will be generated anyway without a SLASH mechanism. For these reasons, it follows that topic and gap are not syntactically connected. Korean topic clause constructions are neither filler-gap construction proposed by Pollard and Sag (1994) nor adjunction suggested by Gunji (1987). The left-dislocation in Catalan analysed by Engdahl and Vallduvi (1996) in Information Packaging could be more satisfactory. But English as for construction is more like Korean topic clause constructions. Unlike, topic clauses and wh-interrogatives, Korean relative clauses are real unbounded dependencies. An important piece of evidence is that missing constituents can be embedded deeply and the relative suffix nun is in the highest verb next the head noun. This is similar to missing constituent and relative pronouns in English relative clauses. Unlike externally-headed relative clauses, internally-headed relative clauses are not real relative clauses in two reasons: internally-headed relative clauses do not stem from those of nun-marked verbs and they are not modifiers as only a single IHRC can combine with kus.