不動產共有人擁有不動產所有權的應有部分，且可以自由處分該應有部分，自然也包括可以拋棄應有部分，本無疑義。只是一旦不動產的共有人拋棄應有部分，隨之而來的就會加重其他共有人的經濟上負擔，因此德國聯邦法院（BGH）在1991年及2007年的判決中，相繼認為「不動產共有人不可以自由拋棄應有部分」，遂引起德國法界的爭議。但由本文所整理的德國立法資料，可知應有部分的拋棄，是德國民法（BGB）自1900年立法以來，自始就充滿爭議的難題，學說有各自不同的解讀，而無法獲得明確的解釋。雖然「不動產共有人拋棄應有部分」是一充滿爭議性的議題，但基於不動產所有權的高價值性，因此「不動產共有人拋棄應有部分」，在德國實務並不常見，因此雖有爭議，但也未見發生重大影響。令人訝異的是，「不動產應有部分的拋棄」在我國法界卻從未發生過爭議，而被視為理所當然。該「理所當然」的原因，勢必必須透過我國相關法律規定，加以探究，始能得知何以如此。因此本文整理德國法界的相關爭執點，而以本國法規定，特別是以我國土地法相關規定，就三部分為討論：一、應有部分的權利性質是否可以和單一所有權般，等同視之，故而共有人可以自由拋棄其應有部分？二、拋棄應有部分有無規避共有的分割制度？三、拋棄應有部分，是否會不利於其他共有人，故而為法所不許？以此三點，分析相關的德國法界意見可否適用於我國相關法律規定。

The co-owner of the real property owns the due part of the ownership of the real property, and can freely dispose of the due part, and naturally includes the right to discard the due part, which is no doubt right. It’s just that once the co-owner of the real estate abandons the due part, it will increase the financial burden of other co-owners. Therefore, the German Federal Supreme Court (BGH) in its judgments in 1991 and 2007 successively held that “the co-owner of the real estate cannot freely abandon what you deserve”, which caused controversy in German law circles. However, according to the German legislative materials compiled in this article, it can be seen that the abandonment of the due part has been the fully controversial problem since the German Civil Code (Bürgerliches Gesetzbuch, BGB) was enacted in 1900. The doctrines have their own different interpretations, and no clear explanations can be obtained. Although “a real estate co-owner discards due parts” is a controversial issue, based on the high value of real estate ownership, “the co-owners of real estate abandon due parts” is not common in German practice, so that it is controversial, but not arousing major discussions in German legal circles. What is even more surprising is that “the abandonment of the due part of real estate” has never been disputed in the legal circles of our country, and it is taken for granted. The reason for this “reasonable” is bound to be explored in accordance with the relevant laws and regulations of our country. Therefore, this article sorts out the relevant disputes in the German legal circle, and discusses three parts based on the provisions of the domestic law, especially the relevant provisions of the land law of our country: 1. Whether the nature of the rights of the due part can be regarded as equivalent to single ownership, so the co-owners are free to discard their due part? 2. Does the abandonment of the due part circumvent the system of the common division? 3. Will abandoning the due part be detrimental to other co-owners, so it is forbidden by the law? Based on these three points, I will analyze whether the relevant opinions of German legal circles can be applied to the relevant laws and regulations of our country.