State Detention Centers (Rutan) in Indonesia have a high level of problems, one example is the problem of overcapacity. The impact of prison overcapacity includes suboptimal guidance and difficulty in supervising prisoners. In addition, overcapacity also has an impact on the fulfillment of rights. The method used in this research is Empirical Juridical. Juridically by examining the laws and regulations relating to the fulfillment of the rights of prisoners in detention centers. Empirically by looking at the reality in the field related to the problem to be studied from the point of view of the application of the law. This research will discuss the impact of overcapacity on the fulfillment of prisoners' rights and efforts to optimize them at the Ponorogo Class IIB Detention Center. Based on the results of the research, the rights of prisoners affected include the right to worship, the right to care, the right to develop potential, and the right to health services. The Ponorogo Detention Center has made efforts to optimize the fulfillment of prisoners' rights, one of which is the social reintegration program, namely the provision of remission and assimilation.