This study aims to know Turkish foreign policy objective in the Mosul Liberation Operation in Iraq from 2015 until 2016. As it is known that the government of Turkey has decided to involve in that military operation even though without permission of Iraqi government. Turkey’s involvement was evidenced by sending troops and giving military training for Peshmerga and Sunni militia called Nineveh Guard. Research method that is used by author is qualitative data collection technique by using secondary datas such as books, journals, newspapers, articles from books or internet related to this research. In this study, author uses Foreign Policy Theory by K.J. Holsti. According to the used theory, the results of this study show that Turkey involvement in the Mosul Liberation Operation based on two objectives, which are core objective and middle range objective