Legal Protection of the Marine Environment from Oil Refinery Industry Activities in Indonesia aims to analyze the form of integration of environmental law principles in oil refining industry activities in Indonesia, the operationalization of the oil refinery industry which has the potential to cause pollution of the marine environment, as well as forms of countermeasures taken against oil spills into the marine environment. The research location is carried out in the oil refinery industry in Indonesia, especially at the PT. Pertamina (Persero) RU V Balikpapan, and PT. Pertamina (Persero) RU IV Cilacap. The research method used is empirical legal research, with a sociological, conceptual, and statutory approach. Empirical data were obtained through interviews and the distribution of questionnaires to selected respondents, while primary legal materials, secondary legal materials, and tertiary legal materials were obtained through literature study. The empirical data and legal materials obtained were analyzed using content and qualitative analysis.Based on the research conducted, the results were found: (i) the integration of environmental law principles in the oil refining industry activities in Indonesia is carried out through licensing mechanisms in the management, processing, transfer, storage, utilization, disposal and/or landfill waste generated by the production process that takes place in the oil refinery industry; (ii) The operation of the oil refinery industry has the potential to cause pollution of the marine environment because the industrial waste produced is dumped into the sea. In addition, the use of the sea as a means of transportation in loading and unloading activities at the jetty (jetty) and Transfer Ship to Ship (TSS) on the high seas can result in spills of crude oil and fuel oil into the sea which has the potential to cause pollution to the marine environment. Likewise, the potential for leaks from undersea pipes used to transport crude oil from the raw material storage terminal to the processing process also has the potential to cause pollution to the marine environment; (iii) handling of oil spills into the sea from oil industry activities is carried out by implementing a management system for dealing with oil spills to the sea contained in the Standard Procedures made by the Company, the substance of which is to implement the provisions contained in the laws, agreements, and Cooperation, as well as international agreements and standards. Keywords: Legal Protection, Marine Environment, Oil Refinery Industry. DOI: 10.7176/JLPG/115-09 Publication date: November 30 th 2021