The purpose of this study is to examine the semantic syntax and pragmatics of the adverb `yeokan` which shows the peculiar negation scope and scalar implicature. The main contents of this study are such as followings. First, there is no negation ambiguity in `yeokan` sentence, since the negatives negate only the meaning of `yeokan`, not predicate. Second, when `botong, imanjeoman, wenmankeum` as well as `yeokan` which have the meaning, `middle degree`, in common combine with negatives, the meaning `middle degree` is negated and the more high rank degree is implicated, so the meaning of sentence become affirmative in spite of the existence of negatives. Third, `yeokan` exhibit the `concession` scalar implicature in the main clause of complex sentence and `-eoyaji` sentence. Fourth, `yeokan gomin-ida` as well as `yeokan gomin-i anida` can be used equally, that is, there exist the change of use which have no negatives in `yeokan` sentence. Fifth, the `yeokan` sentence is `emphasis` sentence in itself, as `yeokan` is mostly used in the main clause of complex sentence and tag question without grammatical device, `yeokan` sentence is replaced with cleft sentence and combined with focus marker `-ga/-lul` On the basis of upper arguments, we come to a conclusion like these, if NPI is negativeness emphasis marker which strengthens the degree of negativeness, `yeokan` is affirmativeness emphasis marker which strengthens the degree of affirmativeness.