摘要:This paper presents a series of empirical analyses of information-security investment based on a reliable survey of Japanese enterprises. To begin with, after showing our methodology for representing the vulnerability level regarding the threat of computer viruses, we verify the relation between vulnerability level and the effects of information security investment.Although in the first section there is only a weak empirical support of the investment model, one can understand that the representing methodology is worth attempting in empirical analyses in this research field. In the second section, we verify the relations between the probability of computer virus incidents and adopting a set of information security countermeasures. It is shown that “Defense Measure” associated with “Information Security Policy” and “Human Cultivation”has remarkable effects on virus incidents. At the last step, we analyze the effect of continuous investment in the three security countermeasures. The empirical results suggest that virus incidents were significantly reduced in those enterprises which adopted the three countermeasures both in 2002 and in 2003.