We witness now the changing techno-economic paradigm and the emerging learning economy. Reflecting on these changes, the group of Evolutionary Economists study recently the theory on regional innovation system, but their research results are still now not theoretically ‘systemized’. Moreover, they often indeed speak of the ‘social capital’, but do not investigate that. This paper tries to systemize their empirical findings and theoretical results and integrate the discussions on social capital in fields of sociology into a mathematical model. This study emphasizes the role of social capital in the innovating process.