國際私法中先決問題之目的在追求涉外民事案件判決之個案妥適性，此乃二十世紀以降，世界各國之國際私法選法規則之發展方向。我國文獻關於先決問題之意義與要件於論述上有分歧之處，法院判決對此亦有概念不清之處，故本文首先整理我國文獻與法院判決關於先決問題一詞之意涵，建構較清晰之相關名詞體系。其次介紹部分問題、第一問題與先決問題之區別；部分問題與第一問題皆依據法庭地之國際私法選定其準據法。其後論述先決問題之要件，探討英國學者Dicey氏與Morris氏主張之三項要件應如何闡釋，將先決問題類型化為「普通之先決問題」與「棘手之先決問題」，前者依據法庭地之國際私法選定其準據法即可，以簡化先決問題之處理，後者之準據法選擇應彈性為之，以追求個案妥適性。本文亦對於誤用先決問題概念之法院判決為評析。

The purpose of preliminary question in private international law is to search for the appropriateness of verdict for civil cases concerning foreign affairs, which is the trend for choosing rules in the application of private international law since the 20th century. There are disagreements in argument regarding the meaning and element of preliminary question in our domestic literatures while court verdicts are also not clear in concepts. First, this paper reviewed literatures in Taiwan and court verdict concerning the meaning of preliminary questions in order to construct a clear system in nouns. Secondly, the differences among partial question, the first question and preliminary question are introduced. Partial question and the first question are based on the applicable law selected by private international law that applies at where the court locates. Then, elements of preliminary question are discussed in order to examine the interpretation of three elements suggested by English scholars Dicey and Morris. Preliminary questions are categorized into ”common preliminary questions” and ”troubled preliminary questions”. The former type of question is based on the applicable law selected by private international law that applies at where the court locates so that the preliminary questions can be handled in a simple way; for the latter type of question, the selection of applicable law should be flexible in order to pursue case appropriateness. This paper also provides comments and analysis concerning court verdicts that have misused concept of preliminary questions.