本文想探討造成高失業率現象的原因。一些曾得出高失業率結論的文 獻，如Diamond(1982a),Howitt & McAfee(1987)及Diamond & Fudenberg(1989)，有的 模型的高失業均衡點有穩定性的問題，有些模型則對個人的尋找意願作限制。本 文試圖重新建立一個均衡尋找模型以解釋高失業率的形成原因，且使此模型得以 免除不穩定的缺點。我們建立了一個較文獻上一般化的尋找方式(searching technology)，不對個人的尋找意願作限制，因此個人可以決定其最適的尋找程度。 由個人的最適行為，我們可以發現，其最適的尋找程度不但取決於參與條件 (participation condition)，更取決於誘因配合條件 (incentive compatibility condition)。 在模型均衡時，我們得到一個穩定的高失業率均衡。這裡的穩定性是指，當經濟 在起始時的就業水準低於某一門檻值時，經濟體系會慢慢的趨向於此高失業均 衡。造成此一高失業率均衡的直覺理由是，失業的工人及有空缺的廠商雙方都沒 有足夠的動機努力尋找工作機會或招工募工人。我們也探討了一些政策含義。其 中一個重要的政策含義乃是，為了減少失業問題，政策應該以能激勵失業工人努 力尋找工作及企業家積極物色工人的動機為方向。

　　　　　This paper studies why high unemployment results and the policies. In thesearch equilibrium literature on the issue of high unemployment [e.g.,Diamond (1982a) , Howitt & McAfee (1987) , and Diamond & Fudenberg(1989) ] , some models have stability problems, and some impose restric-tions on individvals' search intensity. This paper develops a search equilibrium model to generate large and persistent unemployment without stability problems. This model has a more general searching technology thanwhat the existing works do so that individuals will decide their optimalsearching intensity. We find from individuals' optimal behavior that optimal searching intensity is based not only on the participation condition but also on the incentive compatibility condition. We get a stable high andpersistent unemployment equilibrium in the sense that the economy will converge to this equilibrium if the initial employment rate is below a shreshold. The reasons resulting in this equilibrium is as follows. Both sides of unemployed workers and vacant firms do not make sufficient searchingand recruiting effort respectively. We also investigate some policy implications. One of the important policy implications is that policies should bedirected to stimulate the unemployed workers' incentives to search jobsand the vacant firms' motives to recruite workers.