This study examines the policymaking process of child poverty measures in Okinawa Prefecture from the perspective of the constructionist approach to social problems. In Okinawa, the government’s financial support for child poverty measures, the Okinawa Child Poverty Emergency Project (OCPEM), has stimulated the activities of NPOs and is therefore regarded as the “Okinawa Model,” which represents a pioneering example of the positive impact of government financial support on the activities of NPOs. Nevertheless, while the “Okinawa Model” acknowledges the interconnection between the OCPEM and the US military base, it is contended that an examination of these two issues should be conducted separately. As a result, it was not possible to provide a detailed and systematic clarification of the policy formation process or to examine the reasons behind the emergence of child poverty measures in Okinawa Prefecture in a manner that differed from that observed in other regions. Thus, this paper elucidates the diachronic formation of OCPEM policy through document analysis. The analysis is based on Best’s (2017) perspective on the social problem process, which suggests that OCPEM was shaped by the convergence of three policy streams: problem recognition, policy advocacy, and policy proposal. This will demonstrate that it is not feasible to examine the government’s financial support policy isolated from the issue of the US military base and poverty measures. This paper then highlights the need to consider the impact of citizens’ participation in NPOs when addressing child poverty in Okinawa Prefecture.