違章建築數量已成台北市政管理待解決之一大問題。自民國73年市府展 開違建取締工作迄今，平均拆除率約55.96。換言之，每年約有44.04之違建累積 存活下來，致使台北市違建管理陷入嚇阻力不足、欲違犯者俟機而動之窘境。本 文運用成本效益分析與吸收性馬可夫鏈，評估出台北市違建物各年齡狀態移轉機 率、違建物預期生存年齡;利用貨幣化與個案分析，計算違建物提供租賃下預期 貨幣損益情形，藉以探討現行台北市違建管理下產生之取締效果。研究結果擬提 供政府修訂法令罰責及建立違建管理模式之參考。

　　　　　The excessive quantity of illegal constructions had become a serious municipal problemin Taipei. After the prohibitive actions from 1983 till now, the remove rate is averaged at 55.96, inanother word, it also represents the accumulation rate which achieves 44.04 per year. This have been conducted the deterrence force from authority to be insufficient, also to be risk-less to the intensive offenders. This research is trying to adopt both "cost-benefit interpretation" and "absorbing Markov chain" to estimate the illegal constructions' average lifetime, then apply the conception of "capitalization" to figure out the net present value of their profit or loss in case that the illegal construction is go for "rent". We are trying to use the analysis conclusions to evaluate the effectiveness of Taipei's prohibition policy for the illegal constructions, and also furnish for: 1)the reference of retifing the law, 2)the reference of improving the execution for prohibition policy.