This study aimed to analyze the correlation between writing self- efficacy of high school students and the outcome of their descriptive type and essay type assessment. The result of the research demonstrated that there was no significant correlation between writing self-efficacy and the outcome of descriptive type assessment, and that there was low positive relationship between writing self-efficacy and the outcome of essay type assessment. Second, the correlation between the outcome of descriptive type assessment and that of essay type assessment was rather high. Third, the analysis of group correlation according to students' gender showed that male student group had higher correlation compared to female student group. That is, male student group showed statistically significant correlation between writing self-efficacy and the outcome of essay type assessment, as well as between the outcome of descriptive type assessment and that of essay type assessment. On the other hand, female students had higher tendency of inconsistency between their actual writing ability and writing self-efficacy compared to male students. Fourth, the analysis of group correlation according to students' writing level-high, intermediate, and low-illustrated that all correlations of high level student group was meaningfully high, whereas the correlation of the other two groups was not.