State-building is currently considered to be an indispensable process in overcoming state fragility: a condition characterized by frequent armed conflicts as well as chronic poverty. In this process, both the capacity and the legitimacy of the state are supposed to be enhanced; such balanced development of capacity and legitimacy has also been demanded in security sector reform (SSR), which is regarded as being a crucial part of post-conflict state-building. To enhance legitimacy, the importance of democratic governance is stressed in both state-building and SSR post-conflict countries. In reality, however, the balanced enhancement of capacity and legitimacy has rarely been realized. In particular, legitimacy enhancement tends to stagnate in countries in which one of multiple warring parties takes a strong grip on state power. This paper tries to understand why such unbalanced development of state-building and SSR has been observed in post-conflict countries, through a case study of Rwanda. Analyses of two policy initiatives in the security sector – Gacaca transitional justice and disarmament, demobilization, and reintegration (DDR) – indicate that although these programs achieved goals set by the government, their contribution to the normative objectives promoted by the international community was quite debatable. It can be understood that this is because the country has subordinated SSR to its state-building process. After the military victory of the former rebels, the Rwandan Patriotic Front (RPF), the ruling elite prioritized the establishment of political stability over the introduction of international norms such as democratic governance and the rule of law. SSR was implemented only to the extent that it contributed to, and did not threaten, Rwanda’s RPF-led state-building.