本論文以LARP at SCU語料庫為資料，分析臺灣人日語學習者在作文中使用補足型接續詞「実は」的錯誤類型，並探討其背後可能的形成原因。分析的結果發現，主要錯誤類型有以下幾種；在不必要的地方過度使用「実は」、與「しかし」「もっとも」「本当は」「つまり」「実際は」「実際」「事実」等接續詞以及副詞的混同、缺乏轉折的接續詞或接續助詞、缺乏句尾的情態形式「のだ」、以及時貌的錯誤等。另外，比對了「実は」與中文翻譯“其實”的結果發現，在學習者的錯誤類型與“其實”的用法上有極高的相似度，因此推測，學習者在不清楚「実は」的正確用法之情況下，會把「実は」與“其實”等中文譯語直接連結使用。但是在共現限制、副詞的功能語義、以及接續功能上，「実は」與中文譯語都有所差異，因此可能會受到母語的干涉，導致使用範圍較廣的中文譯語產生負向的轉移。

The purpose of this study is to identify common errors and causes of "Jitsuwa" that appeared in LARP at SCU corpus by Taiwanese learners o f Japanese. The result of the analysis shows there are three types of errors; 1) the overuse of "Jitsuwa", 2) confusion with other adverbs and conjunctions that include "Shikashi" and "Mottomo", "Hontouwa", "Tsumari", "Jissaiwa", "Jissai" and "Jijitsu", 3) the lack of adversative conjunctions and the modality marker "Noda" which co-occur with "Jitsuwa", and the error usage in the aspect. Furthermore, as I compared "Jitsuwa" with the Mandarin equivalent "Qishi", the result shows much similar between the types of errors and the usages of "Qishi". Therefore, I speculate the errors were mostly caused by the differences between "Jitsuwa" and Mandarin equivalent "Qishi"; especially in that the co-occurrence restrict ion, the meaning as an adverb and the conjunctive function.