It seems that security police's business to secure safety of state and citizens has existed since the mankind began to create a community. State was not fully responsible for such security business from the beginning. The business was carried out autonomously by the private sector for a long period. However, as the state system had been strengthened, the public sector absorbed the function. But in the modern society where various risks exist, safety of society could not be guaranteed only by public police. Accordingly, cooperation with the private sector is indispensable. In the limit of public police, autonomous organization of security companies and general citizens is expanding its scope. As a result, they should exercise partnership as a tripod to build social safety net. Security police failed to secure manpower exclusively responsible for security, despite various businesses and excessive mobilization. Accordingly, their professionalism and ability to cope with crisis are being questioned. In particular, efficiency of security police is becoming a more urgent issue in an era of international terrorism. Private sector can be classified into security companies and private autonomous organization. In case of security companies, the problem is quality and business ability of guards compared to a rapid external growth such as quantitative expansion and advancement into various businesses. In terms of pure private activity, the necessity of understanding of public police activity and conditions for organizational and continuous activity should be prepared. To tide over such problems and effectively achieve the common goal, changes in the method of employment, new establishment of security police department, and strengthening of professionalism and crisis management ability are necessary in the public police sector. In case of security companies, improvement of relations with public police through joint education, strengthening of business ability and activation of business cooperation through these matters are necessary. To maximize activity of pure private sector, it needs to establish reserve police, manage such private autonomous organization and bolster publicity with citizens. Key Word : Security Police, Private Sector, Security Companies, Security Guard, Private Autonomous Organization