資訊科技的進步與發展改變了企業的營運模式也創造了企業的新獲利模式。然而，企業也面臨了保護資訊安全的威脅與挑戰。2016年我國銀行業ATM盜領事件以及2017年勒索病毒的攻擊，震驚全臺灣。駭客入侵、個資外洩頻繁登上媒體版面，也讓臺灣企業及政府不得不開始重視資訊安全。本研究蒐集2006年至2017年臺灣資訊安全事件，分析其對臺灣上市櫃企業市場績效及會計績效之影響。本研究實證結果發現：在市場績效方面，考量媒體報導的因素後，有報導或報導長度大於三天且發生資訊安全事件的公司相對於沒有發生資訊安全事件的配對公司短期累積異常報酬顯著較低。而在會計績效方面，發生資訊安全事件的公司相對於沒有發生資訊安全事件的配對公司當年以及次年資產報酬率(ROA)顯著較低。因此，本研究認為資訊安全事件確實為臺灣企業產生負面之影響，本研究期望臺灣企業能正視資訊安全的重要性，投入資訊安全維護。;The advance and development of information technology has changed the business model of the company and also created a new profit model for the company. However, companies also face the threat and challenge of protecting information security. In 2016, the bank’s ATM theft in Taiwan and the Ransomware Attacks in 2017 shocked Taiwan. As we saw considerable news about Hacker invasions and data losses recently, Taiwanese companies and governments have started paying attention to information security. This study collects information security breaches in Taiwan from 2006 to 2017, and analyzes its impact on market performance and accounting performance of Taiwan listed companies. The empirical results of this study show that: in terms of market performance, considering the factor of media coverage, if the information security breaches were reported or reported more than three days, the company′s short-term cumulative abnormal returns relative to those without information security incidents are significantly lower. In terms of accounting performance, the return on assets (ROA) of the companies that have information security breaches are significantly lower in the current and following year than the companies that do not have information security breaches. Therefore, this study believes that information security breaches do have a negative impact on Taiwanese companies. This study hopes that Taiwanese companies can put emphasis on the importance of information security and invest in information security maintenance.