本文主要以2001年到2007年間企業公開收購與一般併購案例為研究對象，對公開收購與一般併購宣告併購雙方股東財富影響之比較；並探討公開收購目標公司內部人持股穩定度與防禦策略採行對股東的影響。本文採事件研究法與次級資料分析法為研究工具。研究結果發現，公開收購之併購雙方其股本與收購交易金額均較一般併購活動雙方來的高，公開收購的倂構雙方宣告日後之累積報酬均較一般併購高。公開收購目標公司宣告日附近窗口期皆正顯著，相反的，一般併購目標公司其宣告日附近窗口期累積異常報酬為正向不顯著，顯示公開收購宣告對目標公司股東財富影響較大。公開收購其主併公司宣告日附近窗口期累積異常報酬為正向不顯著，一般併購主併公司宣告日附近窗口期累積異常報酬為負向顯著。當公開收購公司內部人持股率不穩定時，較容易遭受到敵意收購，而當內部人持股率穩定或變異不大時，公司易成為善意公開收購的對象。而防禦策略對目標公司股東財富反而成為負面的影響。 This paper uses Taiwan as a case study to discuss tender offering and mergers. We exam the difference of shareholder''s wealth of acquirers and targets company from tender offering and mergers. In addition, our case study discusses how the change of stock right structure and takeover defenses affect company. This text studies two parts of analytic approach of the law and secondary materials in order to study tools with the incident mainly. In our results, we find shareholder capital stock and purchase trade average amount of money of target company by tender offering acquirers and target is more than that by mergers. Moreover, our case also tells that in tender offering situation, target shareholder’s accumulate abnormal returns is more than that in mergers. Tender offering targeted company declare day window issue all apparent, relatively looks tender offering, the targeted company of general merger does not declare the window one near day for being apparent, it appears tender offering has a great impact on the shareholder accumulate abnormal returns. In addition, tender offering and mergers acquirers company near declare day the window one all not apparent. When being unstable for company, easy to suffer to and hostile takeover, when the stock right is not quite stabilized or made a variation, this company is apt to become the target that good will is tender offering. And it is the negative influence to takeover defenses and accumulate abnormal returns to the company.