This study reviewed primary care purchasing issues of the Indonesian single-insurer, BPJS-K, in the context of triangular power relations between the government, the insurer, and the providers, and considered its challenges of purchasing as the national single-insurer. Some literature reviews and interviews with Indonesian stakeholders and residents were used to describe the historical and social contexts of Indonesian healthcare and social health insurance systems especially focusing legal and institutional status of BPJS-K and primary care provision and delivery conditions in remote areas. Though BPJS-K directly belongs to the presidential office of Indonesia, it has limited power in terms of purchasing as a single insurer. Mainly it was due to the lack of primary care resources, Ministry of Health's strong power as the regulator and provider, and BPJS-K’s powerlessness against monitoring and quality of care assessment. Ambiguous accountability was another issue among the insurer and the Ministry of Health. This created confusions in primary care provision. It is suggested that each agencies’ accountability should be obvious in terms of legal, political, and social contexts.