In this paper, I propose syntactic, semantic and pragmatic restrictions on the distribution of the contrastive topic marker‘-(n)un’in Korean. A contrastive topic is associated with another focus. The association with focus is subject to syntactic islands. On the other hand, there is no syntactic restriction between a phrase attached with‘-(n)un’and a focused expression within the ‘-(n)un’phrase itself. In this area there is a semantic requirement that the alternatives generated by a focused expression be maintained up to the phrase attached with‘-(n)un’. Finally, when‘-(n)un’is used in an embedded clause, the whole sentence becomes natural when the contrastive topic introduced by‘-(n)un’and its alternative contrastive topic, which is presupposed by the contrastive topic marker, jointly constitute a more complex topic which is related to the whole context. And exclusiveness facilitates the formation of the whole complex context.