垂直的系列の役割とその変遷¹

－日本の自動車産業における部品取引構造の長期パネルデータ分析－

抄録

The vertical keiretsu in the Japanese automotive industry, once heralded as a source of competitive advantage, has been losing its foothold since the late 1990s. Yet there remains some argument that some of keiretsu suppliers continue to serve as competitive and indispensable partners for some OEMs. This paper empirically examines the roles of keiretsu suppliers and their changes in the Japanese automotive industry, drawing on a panel data set on 8 components, 12 OEMs and 1,256 transactional dyad units over 32 years. We conduct statistical analysis to examine how keiretsu relations, along with supplier’s competitiveness and prior transactions, affected OEM’s decisions on procurement allocation among suppliers. It reveals that while most OEMs have no longer procured more from keiretsu suppliers since the early 2000s, Toyota continues to procure more after controlling for supplier’s competitiveness and prior transactions. Based on the results, the paper discusses the process in which keiretsu suppliers could survive and gain more procurement from OEMs.