National Assessment of Educational Achievement(NAEA) in Korea, a large-scale national assessment has scored students' constructed-response items through in-hands by gathering in one secured place. This method had a several difficulties such as recruiting raters, booking a large enough places to keep all the raters and test booklets. This study examined the applicability of on-line scoring system for constructed-response items in a large-scale assessment. The performance samples of about 10,000 nine-graders for five subject areas such as Korean, Social Science, Mathematics, Science, English in NAEA were used. Every construct responses were scored by at least two raters. The responses were re-scored when differences between two raters' scores were greater than a certain criterion. The inter-rater reliabilities were above the 0.81, which is a very high. The result of this study shows that the correlations and agreements between scores by two raters were very high, and re-scoring improved the rater consistency even more. This study proved that on-line scoring system would be a stable scoring method of constructed responses for the large-scale assessment.