It is often argued that big five personality especially conscientiousness is necessary for students to be successful in their academic performance and academic achievement. Researchers, educators, and, psychologists have been searching for a set of variables that predicts the patterns of students’ conscientiousness trait and relationship to academic achievement. This study was conducted to find out the correlation between students’ conscientiousness trait and their academic achievement among undergraduate English Language Education students. Using confidence level and confidence interval in doing the sampling selection, 79 students of English Education Department batch 2016 were chosen as the respondents out of 95 students as the total population. The findings of the study revealed that the majority of students had “high” level of conscientiousness trait with the frequency of 24 students classified as students with high conscientiousness and the level of academic achievement was “high” with the mean value of GPA on 3.34. In addition, the significance value (p-value) was on 0.007, meaning that it was lower than 0.05. Therefore, the hypothesis was accepted and it indicated that this research had correlation. When the value of students’ conscientiousness increases, the value of students’ academic achievement will also increase. It means that there is a positive correlation between students’ conscientiousness trait and their academic achievement.