This paper aims to reveal the semantic characteristics of the Korean contrastive focus entailment construction. The findings of this paper under this purpose are as follows. First, ‘khe-nyeng’ construction, ‘ko-sa-ha-ko’ construction, ‘mwul-lon-i-ko’ construction, and ‘mal-hal-kes-to- eps-ko’ construction are named as Contrastive focus Entailment Construction, because the antecedent word and the following word of these constructions are contrastive focus, and a proposition that is expressed by the following sentence of construction entails a proposition that is inferred from the antecedent word of construction. Second, ‘khe-nyeng’ construction and ‘ko-sa-ha-ko’ construction have negative polarity, but ‘mwul-lon-i-ko’ construction and ‘mal-hal-kes- to-eps-ko’ construction don't have. Third, all constructions are combined with ‘to’ in a negative sentence, but the [+negative polarity] types can't be combined with ‘to’ in an affirmative sentence. Fourth, the [+negative polarity] types are not the same as [-negative polarity] types in that in case of [+negative polarity] types, a proposition that is inferred from the antecedent word of construction doesn't consist of the predicate of the following sentence of construction in a affirmative sentence. Fifth, the [+negative polarity] types can't be presupposed scale in a affirmative sentence, unlike the [-negative polarity] types. Sixth, while the [+negative polarity] types select ‘-ki’ noun clause as the antecedent word of construction, the [-negative polarity] types choose ‘-um’ noun clause as the antecedent word of construction. Seventh, these differences between the two types result from negative polarity.