The paper distinguishes the effects of floor area ratio(FAR)constraints on residential land prices into two sides. One is the direct effect of FAR on land price itself, the other is the indirect effect of FAR of adjacent land via the amenity of neighborhood environments. This view, in addition to the assumption that the residents' preferences of housing area and environmental amenity would change in different income levels, could judge the residents' preferences by the direction of the total effects of FAR on land prices. The empirical result shows that residents prefer housing areas to environmental amenities in Taiwan, even Taiwan is highly developed in economy.