A essay test writing was administered to North Korean refugee students in elementary, middle, and high schools two times as a pre-test and post- test, and the aspects were analyzed. In order to suitably interpret and evaluate the success levels of the North Korean refugee students’ writing, SPSS 23 was used as the analysis tool, and the standards for the essay test writing suggested by Spandel & Culham(1996) were adapted and applied as the comprehensive evaluation standards of three areas, namely content, organization, and expression. The results from both the pre-test and post- test showed that there were differences in the aspects of writing development between the students in elementary school and the students in middle and high school. The results in the area of content among matching samples of elementary students showed an increase of 10 points on a hundred percentage scale, from the pre-test average of 2.12 (or 42/100) to the post-test average of 2.62 (or 52/100). However, scores in the areas of organization and expression decreased slightly compared with the scores from the pre-test (0.2 points in organization, 0.3 points in expression). To find out whether or not these scores showed a significant difference, a t-test was conducted and the results showed that all three areas were insignificant. On the other hand, in the case of middle school students and high school students, the scores in organization were the lowest on the pre-test; however the results of the post-test demonstrated an overall improvement in all three areas of content, organization, and expression. The results of the score change in matching samples among middle school students showed score changes: 1.40 (or 28/100) in content, 1.00 (or 20/100) in organization, and 0.60 (or 12/100) in expression. The results of a t-test confirmed that there was a significant change in the area of content. There was an even larger score change in the results of the score change in matching samples among high school students. There were changes in scores: 1.14 (or 23/ 100) in content, 2.38 (or 48/100) in organization, and 1.90 (or 38/100) in expression. The results of a t-test showed that there was a significant improvement in all three areas - content, organization, and expression. In particular, there was more improvement in terms of change in the area of organization. This confirmed that the fundamental writing activities over 8 months lead to a significant change in writing ability. In particular, there was a greater effect as the class level increased from elementary school to middle and high school. There was a significant improvement among middle schoolers in the area of content, and among high schoolers, in the areas of content, organization, and expression. Through this, it is possible to speculate that the development of writing skills among North Korean refugee students will differ according to age group. Given that there is currently no research reported on the writing development of North Korean refugee students, this research that investigated the changes in writing skill by age group is meaningful.