反壟斷法(我國為公平交易法)上的效率抗辯，是指經營者通過證明結合的效率效果足以抵消或超過反競爭效果而取得反壟斷法豁免。“減損競爭”和“促進效率”這兩大因素的權衡是企業結合反壟斷控制的核心內容。 第一章為引言部分，提出本文的研究動機，並對研究方法、研究限制及論文大綱進行簡要介紹。在第二章介紹效率抗辯定義，及反壟斷法視野下普遍被接受的主要效率類型。第三章對效率抗辯制度在歐美國家的發展作了回顧。第四章則是利用經濟分析方法，計算反競爭效果，再比較分析實質性減少競爭標準和嚴重妨礙有效競爭標準之差異。第五章分三部份，第5.1章提及普遍被採納的效率抗辯模式，主要係一體分析模式、抵消分析模式和混合分析模式三種。並建議基於我國國情和《公平交易法》的相關規定，我國宜採用混合分析模式。第5. 2章就效率抗辯制度的適用標準而言，主要有價格標準、消費者剩餘標準、總剩餘標準和權重平衡標準。第5. 3章建議確立效率抗辯制度的證明標準、證明方法。尤其，就效率抗辯制度的適用條件而言，主要有效率為集中所特有、效率的及時性、效率的可證實性、在壟斷或接近壟斷的集中案件不應適用等要件。第六章建議我國明確建立安全港標準，凡屬於安全港範圍的結合不再作進一步審查。第七章綜合上述的結論，試著對我國效率抗辯制度建立提供建議 。 關鍵字：效率抗辯、事業結合、實質性減少競爭標準、嚴重妨礙有效競爭標準、抵消分析、一體分析、混合分析、價格標準、消費者福利標準、總剩餘標準、權重平衡標準 / The efficiency plea on the antitrust law refers that the intensified efficiency effect proved by the operator is sufficient to set off or stronger than the anti-competition effect so as to be exempted by the antitrust law. Competition impairment and efficiency promotion are two factors need to be traded off during the anti-monopoly control on concentration for business operators. Chapter One presents the motive , approach, framework, scope and limitations of the paper. Chapter Two introduces the definition of efficiency and the main types of efficiency which includes production efficiency, allocative efficiency, dynamic efficiency and other efficiencies. Chapter Three provides a brief history of efficiency plea practices in Europe and the United States . Chapter 4 tries to compare the Substantial Lessening of Competition test (SLC) with Significantly Impedes Effective Competition test (SIEC ) standards and try to prove the SIEC is suitable for our country. Chapter 4 also attempts to analyze anti-competitive effects of mergers by using economic analysis methods. Chapter Five is divided into three sections. Section one analyzes the main types of efficiency defense system models, including the integrated analysis model, offset analysis model and mixed analysis model. Considering the actual situation in our country and in accordance with regulations by the Antitrust Law of Taiwan, a mixed analysis mode is suggested for application. Section two focuses on the welfare standards of price standard, consumer welfare standard, the total surplus standard and the balancing weights standard. Section three recommends that standard of proof and method of proof and types of application conditions shall be established. Especially, the main types of application conditions are efficiency specific to concentration, the timeliness of the efficiency, the verifiability of the efficiency and whether the efficiency defense system is applied in the situation of near monopoly. Chapter Six defines the relevant market and suggest Critical loss analysis should be introduced for the relevant market definition. Chapter Six also suggests to adopt the " strong safe harbor" standard which means that once undertakings belong to the safe harbor range，they will no longer be subject to further review. The final chapter tries to offer some suggestions on the establishment of efficiency defense in Taiwan . Key words: efficiency plea, concentration of undertakings, the Substantial Lessening of integrated analysis model, offset analysis model, mixed analysis model, price standard, consumer welfare standard, the total surplus standard, the balancing weights standard