Styrofoam buoys are the most abundant marine debris item in the coastal areas of South Korea. Participatory workshops to find solutions to the Styrofoam buoy marine debris problem were held in 2011–2012. Policy ideas were created through brainstorming sessions and were discussed in 2011. These policy ideas were depicted on a conceptual model and a results chain framework was further refined in 2012. Some of the policy alternatives developed in these processes, such as ‘increasing obligatory retrieval of old buoys in exchange of subsidy for high-density Styrofoam buoys', were adopted as national governmental policy. Participatory workshops were effective in developing policy measures on marine debris, especially when various stakeholders were involved in the discussion.