There was a new Law in 2009 [1] about hospital that is seeking to improve the quality of health services across all Indonesian hospitals. One of specific attention is mandatory aspect of accreditation process. By using accreditation process the quality of health services will be improved through such criteria and standards for hospitals that are disclosed in other government regulations (such as the Ministry of Health Decree No: 129/Menkes/SK/II/2008). On the other hand, the quality improvement processes are difficult to realize. This is because hospitals have limited resources, such as medical specialists and medical equipment, to meet criteria and standards. Therefore, the objective of this study is to examine how does policy on accreditation influences to the quality improvement in Indonesian hospitals. A qualitative approach is used to explore how policy on accreditation can influence services that influence hospitals on practices and processes in the quality improvement. Results show the four hospitals are used to dealing with the relevant institutions on health services, such as Ministry of Health and the Indonesian Committee on Hospital Accreditation (KARS). There is a strong role from the KARS in improving quality through its accreditation process. This is because the KARS has huge power to control Indonesian hospitals through credentialing and licensing of services as well. To conclude, through the accreditation process, there are many ways to improve the quality of services, such as improvement in activities, data and process of services.