otivation is crucial in the process of teaching and learning. One type of motivation is intrinsic motivation. Intrinsic motivation is categorized into three; intrinsic motivation-knowledge, intrinsic motivation-accomplishment, and intrinsic motivation-stimulation. On the other hand, of the English language skill, writing is one of the productive skills that is a challenging skill. One of types of writing is academic writing. The aims of this study were to investigate the students’ intrinsic motivation, to explore the students’ academic writing skill, and to examine the relationship between the students’ intrinsic motivation and their academic writing skill. This study used quantitative research method and for the design used correlational design. The research hypothesis of this study is alternative hypothesis (Ha). This study used questionnaire and score to collect the data. There were 99 students at batch 2014 at the English Language Education Department at one of the universities in Yogyakarta in the academic year of 2017/2018. The result showed that the level of students’ intrinsic motivation is 3.05. This means that the students had high level in intrinsic motivation. The result revealed that the level of students’ academic writing is 3.51 – 4.00. This means that the students had very good level in academic writing. Therefore, the result on the correlation between students’ intrinsic motivation and their academic writing skill is 0.005. This means that there is positive correlation between students’ intrinsic motivation and their academic writing skill but very low level. It is because the score of correlation coefficient < 0.199. It can be concluded that the alternative hypothesis (Ha) is accepted because the significant (2-tailed) value xii is equal (0.005), so there is correlation between students’ intrinsic motivation and their academic writing skill.