本文旨在探討台灣產物保險業在併購活動後市場結構之變化與產物保險公司經營之績效。本研究以赫芬德指數(Herfindahl Index)來衡量市場集中度之變化，以核保利潤(Underwriting Profit)作為經營績效指標，並採用Mason(1939)、Bain(1956)與Scherer(1970)等人提出的結構行為績效假說(Structure-conduct-performance Hypothesis)以及Rhoades(1985)提出的相對市場力量假說(Relative Market Power Hypothesis)進行市場結構與經營績效間關聯性的分析，研究期間為2000年至2006年。結構行為績效假說提出廠商的獲利主要取決於市場結構，市場集中度與廠商獲利之間存在正向關係；另一方面，相對市場力量假說主張廠商獲利與市場集中度無關，與市場佔有率呈現正向關係。 研究發現：(1)產物保險市場集中度呈現上升趨勢，市場集中度從2000年的0.0800上升至2006年的0.0913，其中保證保險、火災保險、汽車保險、工程保險、責任保險與貨物運輸保險之集中度呈現上升趨勢，而傷害保險、其他財產保險、漁船保險、船體保險與航空保險之集中度呈現下降趨勢；(2)實證結果支持結構行為績效假說，市場集中度與產物保險公司核保利潤呈現顯著正向關係，其p值為0.004。產物保險業經歷併購活動後造成市場集中度上升，併購活動對於經營績效的改善應有正面助益。 / This thesis analyzes concentration effects of merger and acquisition measured by Herfindahl index in Taiwan property-liability insurance industry. The relationships between market structure and underwriting performance are also analyzed for the time period 2000 to 2006 by testing two hypotheses: structure-conduct-performance (SCP) hypothesis which developed by Mason (1939), Bain (1956), and Scherer (1970) and relative market power (RMP) hypothesis which proposed by Rhoades (1985). The SCP hypothesis proposed that concentration is positively related to performance while the RMP hypothesis asserts that market share is positively related to performance. Implications of study results are: (1) Concentration level experiences increase from 0.0800 in 2000 to 0.0913 in 2006. Bonding & credit, fire, automobile, engineering, liability and marine cargo insurances trends to increase in concentration over the time period, whereas accident, fishing vessel, others, marine hull and aviation insurances trends to decrease; (2) The SCP hypothesis is supported. Concentration level is positively related to underwriting performance with p-value of 0.004. Higher concentration level and positive concentration-performance relationship infer that merger and acquisition activities would have positive effects upon firm performance.