不動產先買權的制度運作是實務上重要問題，但既有相關學說研究仍有不足。其中，具物權效力之先買權由於其效力較債權效力先買權為強，對相關當事人影響較大，特別值得關注。不動產先買權的（相對）物權效力究何所指，與一般所謂物權效力是否相同，有待釐清，本文從相關當事人的利益衡量等角度探討之，對既有的學說與實務見解予以回應，並提出解釋論上的建議。關於不動產相對物權效力先買權，首先，本文以為具物權效力之先買權人請求塗銷第三人的移轉登記，實質上就是以意思表示撤銷出賣人與第三人間的法律行為，並因而請求塗銷登記。再者，如第三人已將標的物移轉於原出賣人，具物權效力之先買權人不得直接請求出賣人移轉登記，而亦應請求塗銷第三人的所有權移轉登記。

The system of rights of first refusal of real estate is an important issue in practice. However, the existing studies are insufficient. The effect of in rem rights of first refusal is superior to in personam rights of first refusal and has greater impact on relative parties. Therefore, we should be concerned about the effect of in rem rights of first refusal especially. This study explores the meaning of the effect of (relative) in rem rights of first refusal of real estate and the divergence between in rem rights of first refusal of real estate and general in rem rights from the perspective such as consideration of the interests of the concerned parties. This study also discusses the existing doctrine and practice and makes some propositions in explanation. About the “relative in rem rights of first refusal of real estate”, first of all, this study holds that when the in rem right holder of first refusal claims for registration of cancellation of the ownership of the third party, he revokes the juridical act between the seller and the third party by an expression of intent in reality and claims for registration of cancellation. Furthermore, if the third party has already transferred the real estate to the original seller, in rem right holders of first refusal shall not claim for registration of transfer directly. The in rem right holders of first refusal shall claim for registration of cancellation of the ownership of the third party as well.