While there exists a large volume of research on sentiment classification of English customer reviews using English sentiment dictionaries, there are few researches on classifying sentiment of Korean customer reviews using Korean sentiment dictionaries. We use more than a thirteen thousandword movie domain Korean sentiment dictionary to classify positive/negative sentiment of online movie reviews written in Korean. The binary sentiment classification performance of the constructed sentiment dictionary was 80.7% confirming the effectiveness of the Korean sentiment dictionary and the dictionary-based sentiment classification method.