Today, more and more countries in the world are opening their data to public. As more government data are freely accessible, a question that arises is whether all published data meet the principle of open data. This study aims to evaluate open data implementation on the official government websites in Indonesia, especially at the ministerial level. The observation aimed to assess the level of data openness based on open data principles. This evaluation was conducted using Data Openness Index (DOT). The results showed that out of five levels of data openness index (level 0 to 4), the data openness of ministries websites in Indonesian is at the third level (Average Openness). The analysis of this study suggests that each indicator of DOI need to be considered so that published data are not only available but can also be further utilized to enhance transparency, social and commercial values, and more participatory governance.