The research is taking all Listed and OTC Companies in Taiwan, specifically electronic industry, as subjects. Applying Event Study method on all negative environmental or safety events as examples collected from the years between 2004 to 2016, this study will examine how the negative environmental or safety events will affect stock returns. As the study shows, when a corporate is related to or responsible for the negative environmental or safety events, it will result in stock prices to go down temperately. Secondly, the events will affect differently on both Bear and Bull Markets. Besides, by applying Regression Analysis method, it shows that most significant impact reflects on the Bear Market. Also, the larger the corporation is, the greater the impact will be. However, when it comes to whether the impact is from environmental or safety related events will affect the stock prices almost equally.