Internet environment and innovative ICT(information and communication technology) have brought about big changes to our lifestyle and industrial structure. In spite of the convenience of Internet, various cyber incidents such as malicious code infection, personal information leakage, smishing(sms + phishing), and pharming have frequently occurred. Information security must be recognized as a key and compulsory element for surviving in a global economy. Strategic roles of information security have recently been increasing, but effective implementation of information security is still a major challenge to organizations. Our study examines the influencing factors of information security and investigates the causal relationship between information security maturity level and organizational performance through an empirical survey. According to the results of our study, personal, organizational, technical, and social factors affect organizations‘s information security maturity level altogether. This result suggests that when dealing with security issues, the holistic and multi-disciplinary approaches should be required. In addition, there is a causal relationship between information security maturity level and organizational performance, and organizations aim to establish the efficient and effective ways to enhance information security maturity level on the basis of the results of this study.