本論文是以沼田（2009）學說為基礎，從「焦點助詞」中抽取 mo, wa, dake, shika, sae等 5個助詞來研究台灣的日語學習者運用焦點助詞的情形。本研究針對 LARP at SCU語料庫中 1位學生的作文進行縦向的習得研究分析；分析的內容除了包括焦點助詞的出現順序、使用情形、錯誤使用外，並以中日文句構對比分析的方式來探究誤用的原因。本研究獲致以下結論： 1. 受試者在 1年級時學習的 mo, wa, dake, shika等詞出現在作文中，而2年級時才學的 sae則不曾出現在作文中。mo, wa, dake, shika等詞出現的順序是「対比的 wa」-->「累計的 mo」-->「限定的 dake」-->「限定的 shika」-->「意外的 mo」。 2. 含有 mo的句型使用頻率最高，誤用也都出現在含有 mo的句型裡。 3. 誤用可以歸類成「焦點助詞作用範域的誤認」與「語意格助詞的不当省略」兩種。誤用的原因應該是受到中文裡「也」的句法結構的影響。

The present paper, based on Numata (2009) and focusing on “wa, mo, date, shika, sae,” aims to investigate the circumstances surrounding the learning of focus particles by Japanese learners in Taiwan. The research was conducted on the basis of the LARP at SCU database and examined one student’s compositions over a period of three and a half years, in an attempt to clarify the order of appearance, the way of use and illegitimate uses of these focus particles. Moreover, by comparing and contrasting Japanese and Chinese, we tried to find the causes of the misuses of focus particles. The research has led to the following findings: 1. Focus particles wa, mo, dake, shika, taught in the first year, were used in compositions, while focus particle sae, taught in the second year, never appeared in compositions during the entire period of seven semesters. The order of their appearance shows “wa representing contrast” --> “mo representing accumulation＂ --> “dake representing limitation＂ --> “shika representing limitation,”--> “mo representing surprise.” 2. mo is most frequently used, and misuses appear solely in phrases containing mo. 3. The illegitimate use of these focus particles can be divided into 2 types: “mistake of the scope of the focus particles” and “inaccurate deletion of semantic cases.” And the reasons for the misuse of mo may be due to the influence of yie in Chinese.