This paper describes the methodology of marine accident investigation. The procedure of the implementation of the maritime investigation can be separated in two categories the procedure of implementation of safety investigation and the procedure of implementation of administrative investigation. The conduct of maritime investigation is being done by the investigative body of the state which is the main party of interest. The safety investigation is done separately from the administrative investigation. The planning of the maritime investigation is mainly about choosing the right equipment and the investigators for the job. The approach of investigator towards the human factor is of great importance for the marine accident investigation, marine accident investigator needs to be aware of the trauma that the participant or a witness has been through. Data collection is the main part of marine accident investigation and it depends on the ability of the investigator, the state of mind of the participant or a witness and language barrier. The flow of the investigation will mainly depend on the speed of collecting such data.The marine accident investigation report brings the final insight into the marine accident and the marine accident investigation.