Disaster mental health crisis assistance refers to a series of activities to promote psychosocial recovery of disaster survivors and the community affected by a disaster. Crisis assistance activities are performed at a team level, not at an individual level, and thus it is important to foster trained assistance teams in the community. Yet expert consensus regarding how to cultivate and provide such team training is lacking. The purpose of this study was to develop management guidelines for a Disaster Mental Health Crisis Assistance Team (DMH-CAT) using a Delphi process. In this study, an expert panel was conducted to develop initial items for management guidelines, subsequent to which two structured online surveys were administered to disaster mental health experts who had not participated in the initial item development. Through this process, 84 guidelines across 13 domains were derived. The subsections in the guideline included definition of terms, mission and goals, composition, roles of the team, team leader, and team members in preparation and acute disaster phases, respectively, assessment of team competency and operational systems, education and training, team care and prevention of burnout, and ethics. Overall the level of expert consensus for the final items was high, with a consensus mean of 8.20 on a scale of 1 to 9. The management guidelines of the DMH-CAT developed in this study are composed of items describing general principles that are applicable to various forms of the DMH-CAT.