為能瞭解國內空屋率持續大幅上升，但房價卻調整緩慢的現象，本文中嘗試運用自然空屋率理論來探討自有住宅市場中房價與空屋率的關係，並透過台北市與台北縣1980-2001年的資料估算使房價變動為零的均衡空屋率。實證結果發現，空屋率與房價變動率之間有顯著的反向關係，但就台北市而言，以當期空屋率對實質住宅單價變動率影響的模型較佳，而台北縣則以前期空屋率對名目住宅總價變動率的影響模型較佳，顯示出台北市與台北縣住宅市場在運作上有明顯的差異。本文推估台北市的均衡空屋率值在12.61%至14.03%之間，台北縣的均衡空屋率值在20.56%到22.72%之間，我們可發現不論台北市與台北縣的均衡空屋率均明顯偏高，且與實際空屋率的高峰值差距不大，此可能是造成兩縣市長期房價漲多跌少，房價調整緩慢的原因。至於自有住宅市場的高均衡空屋率，可能與有相當數量的空屋做為第二屋使用或暫時開置，並未在市場參與運作有關。

This paper applied natural vacancy rate theory in rental housing market to clarify the sluggish adjustment process of housing prices to vacancy rate in Taiwan’s owner occupied housing market. The empirical results revealed that vacancy rate had significant negative effect on the change of housing prices. According to the fitness of the model, the current vacancy rate to the real change of housing prices and the lagged vacancy rate to the nominal change of housing total prices is the best model for Taipei City and Taipei County, respectively. It means that the housing market structures of Taipei City and Taipei County are quite different. The estimated equilibrium vacancy rates are about 12.61 to 14.03 per­cent in Taipei City and 20.56 to 22.72 percent in Taipei County. Both equilibrium vacancy rates are extraordinary high and very close to the peak value of actual vacancy rates. These findings can explain the slow adjustment process in Taiwan’s owner occupied housing market quite well.