Abstract
There is ecosystem strategic theory to analyze platform company's strategy that is attracting attention recently (Gawer&Cusumano, 2002; Iansity&Levien, 2004). However, the ecosystem concept often is used somewhat ambiguous. In this paper, we re-define this concept and organize the differences between the two major existing strategic theory, positioning approach and resource-based approach. In addition, we organize our parallel platform concept which authors have presented as a part of the ecosystem theory based on case studies.