Nowadays the characteristics of disaster eventually threaten all over the world by quick industralization, besides the level and size of disaster is getting larger and complexity than before, Thus diverse organizations and groups such as central and local government, related agencies, citizens, NGOs, companies including military are required to be forms as a multi-organizational cooperation system that is against the national disaster. Particular the role of military organization is getting becoming important agency to government. However disaster management is limited to be performed by R.O.K Army so far. and the practical military disaster management system is insufficient supporting by weak legislation and institutions. This research is focused on what attributions of organization structure of military should take to fit the characteristic of disaster. therefore this research deals with concepts of disaster management, organizational structure, contingency theory. The following consists of the research analysis. Firstly, the environment is comparatively stable. The forecasted highly possible characteristics of chronic disaster usually result in a general disaster rescue unit to be deployed in which disaster management utilizes a mechanistic structure which leads to an organizational structure to be formed. The research between Burns & Stalker and Lawrence & Lorsch portray that efficiency is the utmost pursued value. The official regulations are operated through units of definite fields which are stiffly applied with little discretion. The authority structure is being more centralized. Communications is usually done through a vertical passage with downward directions and orders plus upward briefing in accordance of accomplishment. The divisional structure is precise; the divisions are mutually connected so modification and combination consist of hierarchism in which mechanistic structure can be seen to be suitable. Secondly, the environment is very complicated. The lowly forecasted characteristics show acute disaster by customarily professional disaster rescue unit being involved with the disaster management portray an organic structure to be suitable for recuperation. Furthermore, the research undertaken by Burns & Stalker and Lawrence & Lorsch show the ultimate objective for survival is adaptability and division of the environment. The official regulations depend on the flexibility of the situation. The authority structure is becoming decentralized. The modification and integration of specialized divisions are communicated through lateral means of mutual negotiations. The division of structure seems to be indistinct which results in divisions to mutually duplicate. Moreover, the relationship of mutually inter-relying on each division loosens. A considerable sector are autonomic and independently operated, therefore an organic structure can be seen to be appropriate.