本文利用1996年及1991年工商普查製造業資料，研究進入退出、集中度與市場競爭性，實證結果發現影響進入率最主要的因素除預期利潤率外，為市場的需求成長、市場規模的大小及美國的市場需求；進入障礙變數：最小效率規模相對市場規模，資本需求及產品差異性，則會顯著地阻礙廠商進入市場。但研究發展卻是促進廠商進入的因素，成為新廠商進入的一個策略。另外，本文估計的進入障礙程度可發現有些產業為低進入障礙高集中程度，顯示這些產業雖為高集中度但具市場競爭性。

　　　　　In this paper, we provide empirical insights into the relationship between entry, exit, concentration, and market contestability using 1991 and 1996 Taiwan manufacturing census data. The empirical results show that positive net entry will decrease concentration. In addition , entry is motivated by expected profits, market demand growth, market size and the US market growth. The minimum efficient scale to market size, the capital requirement and product differentiation are factors discouraging. Moreover, research and development is a means of entry to markets by new firms. Through the estimation of barriers, we found some industries, which show low entry barriers and high entry, but high levels of concentration. These industries reflect the existence of contestable market.