Objective: It is necessary to develop new guidelines to delineate the best ways of providing psychosocial care to ensure mental health following a disaster. Methods: This study applied the scoping review method as a means of establishing evidence-based guidelines for disaster mental health services. A total of 440 literatures were selected through a scoping review of 20,864 documents. Twenty-three recognized experts were invited to participate in the survey and a two-round online Delphi survey was conducted. Results: The concordance rate in the Delphi Round 1 was 95.1%. Six items were excluded and new items were formulated with experts’ suggestions. A total of 23 statements were slightly modified to clarify their meaning. In the Delphi Round 2, all items were met with consensus. The three items with the highest consensus among the experts were related to the protection of personal information and privacy. The item with the lowest consensus among experts was related to debriefing. Other items were related to establishing mental health support centers and suicide prevention activities. Conclusion: 140 items were developed through scoping reviews based on evidence-based methodology. These items were used to describe the disaster mental health support identified in Delphi. The guideline will provide a foundation for effective preparation and response in disaster situations.