人類的思考決策與行為結果，大多是依循一個明確的市場制度而為的，故市場經濟制度的重要性，就在於有利個人形成如何有效配置資源的合理預期，同時也富有約束及激勵個人行為的誘因，讓個人能在制度約束的條件下，追求自利動機的極大化。都市空地再利用及市地重劃的法令制度，就具有這樣的經濟效應，所以本研究主要在探討，在空地再利用及市地重劃制度的約束與激勵條件下，都市中的經濟人行為決策與個體互動所形成的空間外部性，其會如何反應在住宅土地價格的變動，以探討空地再利用及空地開發所產生的空間外部性對住宅土地價格之影響。本文主要包括（1）空地再利用對住宅土地價格之影響；（2）空地再利用及鄰里土地開發對新建住宅土地價格之影響；（3）空間外部性、交易成本與市地重劃對新建住宅土地價格之影響等。 首先，有關「空地再利用對住宅土地價格之影響」，本文以Geoghegan（2002）的理論模型為基礎，主要探討空地再利用所產生的開放空間效果，其對於住宅土地價格的影響分析。本文運用地理資訊系統及空間計量分析，並建立民國九十三年及九十四年住宅土地的特徵價格模型，研究對象以台南市為例。實證結果發現，公有空地再利用作為公園及臨時停車場使用，其對於住宅土地價格產生正的空間外溢效果，此表示空地再利用所產生的開放空間的外溢利益，其大於空地管理維護的外溢成本。私有空地再利用作為運動場使用，民國九十三年的外部成本大於外部利益，但於民國九十四年的外部利益大於外部成本，故就私有空地再利用的外溢效果而言，私有空地再利用作為運動場使用的外溢效果可由負向轉為正向。公有空地再利用的邊際價格較私有空地再利用的邊際價格為高，故政府應繼續推動公有空地再利用的政策，以彌補鄰里的開放空間不足。 其次，有關「空地再利用及鄰里土地開發對新建住宅土地價格之影響」，本文主要在探討空地再利用所產生的開放空間效果，及鄰里土地開發所產生的空間外溢效果，兩者對於新建住宅土地價格的影響分析，本研究範圍以台南市民國九十三年的新建住宅為對象。實證結果發現，公有空地再利用對於新建住宅土地價格具有正的空間外溢效果，此表示開放空間的外溢利益大於空地管理維護的外溢成本。鄰里土地開發作為住宅使用時，會對新建住宅土地價格形成正的空間外溢效果，但當鄰里土地開發作為工廠使用時，卻會對新建住宅土地價格形成負的空間外溢效果。最有價值的住宅土地為，開放空間數量最大化及土地開發數量的最小化，故當永久性的開放空間(如鄰里公園)、可開發性的開放空間(如公有空地再利用)數量增加，以及鄰里工廠土地開發數量減少等，其將有助提高新建住宅土地價格。 最後，有關「空間外部性、交易成本與市地重劃對新建住宅土地價格之影響」，本文主要從政府實施市地重劃有助於降低交易成本的觀點，探討政府實施市地重劃制度及建設商的土地開發行為所產生的空間外部性，其反應在新建住宅土地價格的影響。本文運用空間計量分析及地理資訊系統，並結合Box-Cox函數轉換，以建構具有空間外部性的特徵價格模型。本文研究範圍以台南市民國八十年、八十五年及九十年的新建住宅為對象。實證結果得知，空間誤差Box-Cox模型對於空間外部性提供良好的解釋力。政府實施市地重劃之後對住宅土地價格具有正向外部性，且有政府參與的重劃區所反應的住宅土地邊際價格為正向關係。而建設商個體互動關係則具有正向及負向外部性，並在長期下出現由正向轉為負向之情況，此證明空間外部性會呈現相互性的現象，進而反應在新建住宅土地價格上會有增減的作用。 / This study mainly assumes that development of vacant land give rise to spatial externalities from the reuse of vacant land and the institution of land readjustment. Finally, this effect will be reflected in the residential land prices. To test this hypothesis, this study applies spatial econometric and geographic information systems based on hedonic pricing model. This study mainly includes that (1) The Impact of Reusing Vacant Land on Residential Land Prices, ( 2) The Impact of Reusing Vacant Land and Neighboring Land Development on Newly-Built Residential Land Prices, ( 3) The Impact of Spatial Externalities, Transaction Costs and Land Readjustment on Newly-Built Residential Land Prices, and evidence from Tainan City in Taiwan. First of all, about’ The Impact of Reusing Vacant Land on Residential Land Prices’, This study is based on Geoghegan’s theoretical model (2002) and focuses on open space effect of reusing vacant land on residential land prices. The data are selected from residential land prices in 2004, 2005. Empirically, I find that the reuse of publicly-owned vacant land used for green and park has positive spatial spillover effects. This means that spillover benefit of open space is more than spillover cost of vacant land management. The reuse of privately-owned vacant land used for sport has negative spatial spillover effects in 2004. The marginal price of publicly-owned vacant land is over than privately-owned vacant land. It is concluded that, the government should continue promoting the reuse of publicly-owned vacant land and used for open space of the neighborhood. Secondly, about’ The Impact of Reusing Vacant Land and Neighboring Land Development on Newly-Built Residential Land Prices’, This study focuses on open space effect of reusing vacant land and spatial spillover effect of neighboring land development on newly-built residential land prices. The data are selected from newly-built residence in 2004. Empirically, I find that the reuse of publicly-owned vacant land has positive spatial spillover effects on newly-built residential land prices. This means that spillover benefit of open space is more than spillover cost of vacant land management. Land development used for residence has positive spatial spillover effects and used for factory has negative spatial spillover effects in a neighborhood. This means that more the reuse of publicly-owned vacant land will increase newly-built residential land prices, while more land development used for factory will decrease newly-built residential land prices in a neighborhood. Finally, about’ The Impact of Spatial Externalities, Transaction Costs and Land Readjustment on Newly-Built Residential Land Prices’, This Study mainly assumes that land readjustment can reduce transaction costs in terms of the spatial externalities from developers’ behavior and the institution of land readjustment. This effect will be reflected in the newly-built residential land prices. To test this hypothesis, I apply spatial econometric analysis and geographic information systems based on the Box-Cox hedonic pricing model. The data are selected from newly-built residence from between 1991, 1996 and 2001. Empirically, I find that the spatial error Box-Cox model is appropriate for engaging in spatial externalities analysis. This is because the results show that land readjustment gives rise to positive spatial externalities on newly-built residential land prices and the marginal price of residential land in areas where land readjustment takes place is also positive. The effects of developers’ interactions give rise to positive spatial externalities but these change to negative spatial externalities in relation to newly-built residential land prices in the long term. It is concluded that, land readjustment as implemented by the government really does contribute to reducing uncertainty in the land development process, and also reduces transaction costs between construction practitioners and landlords.