It has been long pointed out that the start-up environment in Japan is unfavorable. In order to mitigate this issue, discussion on factors such as funding, human resource development, and institutional aspects have been taking place, and various policy measures have been implemented. The number of firms, however, is still spread unevenly. I will analyze entrepreneurs' network by focusing on social network services (SNS). Entrepreneurs' network including alumni, professional acquaintances and incumbent business partners might play a pivotal role in the performance of their firms as it provides crucial business information. I will look into how entrepreneurs' network will expand and its significance.