Abstract
Importance of business strategy of platform company in the software product and service market is considered increasing. In this paper, we focus on the platform envelopment as a market entry strategy, giving theoretical explanation, and consider the strategy aims to counter the platform envelopment from the opposite stance. Based upon two case studies, we confirm that in multi device environment, platform envelopment from OS layer is less successful. Also, we present cross-device implementation strategy as a counter-strategy.