In this paper, the accident-inducing effects of strategic change which is intended to adapt to environment flexibly are examined. Unlike previous studies in which accidents were commonly attributed to operational malfunctions or errors, we draw attention to the accident-inducing effects of strategic factors associated with strategic changes, such as niche change, structure change, and core strategic resource change. We suggest that these particular factors, while increasing flexibility, may also cause an unintended increase in the risk of accidents because they reduce reliability and increase complexity. The results of our analysis of accident rates in the U.S. airline industry from 1978 to 2011 showed that these three strategic factors affected the occurrence of accidents positively, as predicted in our hypotheses.