有程序瑕疵的區分所有權人會議決議效力，涉及每一區分所有權人的權益與決議的穩定性，是理論與實務上的重要問題。本文先總說其效力，再分別針對「區分所有權人會議決議程序瑕疵違反之事實非屬重大且於決議無影響」、「對區分所有權人會議決議程序瑕疵未當場表示異議」與「區分所有權人訴請撤銷決議有其他違反誠信原則的情形」，分析有程序瑕疵的區分所有權人會議決議效力。本文著重於成本效益分析與相關當事人的利益衡量，就既有的學說、實務見解及修正草案予以回應，並提出解釋論與立法論上的建議。本文以為，區分所有權人會議決議召集程序或決議方法，違反法令或規約時，區分所有權人得於決議後三個月內訴請法院撤銷其決議；區分所有權人對召集程序或決議方法，未當場表示異議者，不得訴請撤銷。如程序瑕疵的情形非屬重大且於決議無影響，則法院得駁回撤銷決議之訴。 The effect of the procedurally defective decision made by the unit owner assembly is an important issue in theory and practice due to its great influence on the interests of every unit owner and the stability of the decision. This study first explores the aforementioned effect in general before analyzing it under the following circumstances: ＂the fact of violation is insignificant and will do nothing to the prejudice of the decision＂, ＂the unit owner did not make objection to the procedure at the meeting＂, and ＂the unit owner who applied to the court to revoke the decision violates other good faith requirements.＂ The cost-benefit analysis is then stressed and the interests of the concerned parties are emphasized. This study further discusses the existing doctrine, practice, and the draft amendment and makes some propositions in explanation and legislation. In this study, it is suggested that if the calling procedure or the method of a decision made by the unit owner assembly violates the act or regulation of the condominium, a unit owner may apply to the court to revoke the decision within three months after the decision, except the unit owner who did not make objection against the calling procedure or the method of the decision at the meeting. Upon receipt of the petition for annulment of a decision, should the court considers that the fact of violation described in the said petition is insignificant and will do nothing to the prejudice of the decision, the court may dismiss such petition.