本研究は、英語学習者である日本人大学生を対象に自由記述式のアンケートを実施し、大学入学前の中学校と高等学校の6年間に、どのような要因で英語学習の動機づけが高まったのか、また減衰したのかを探索することによって、英語学習に関する動機づけを行う方策についての示唆を得ることを目的とする。最初に、先行研究に基づいて動機を高める要因と減衰させる要因をまとめる。次に、これらの要因と動機の変容について探究しようとした先行研究を概観し、研究方法上の問題点を指摘する。先行研究の問題点を克服するために本研究は計画された。 In recent research on L2 learning motivation, there have been an increasing number of studies on motivators (e.g., Cheng & Dörnyei, 2007; Guilloteaux & Dörnyei, 2008; Sugita & Takeuchi, 2010) and demotivators (e.g., Kikuchi & Sakai, 2009; Sakai & Kikuchi, 2009) in the classroom. Although findings from these studies give general guidelines to language teachers, it has been argued that the motivators and demotivators vary in different contexts and that learner motivation fluctuates (Hayashi, 2005; Miura, 2010; Sawyer, 2007; Shoaib & Dörnyei, 2005). This study was aimed at understanding the changes in motivation among Japanese learners of English during their 6 years of high school. Based on a survey of 199 college students taking an English language teaching certificate class in the spring semesters of 2006, 2007, and 2008, the general pattern of changes as well as reasons for change were investigated. In a questionnaire adapted from Sawyer (2007), participants were asked to reflect on their level of motivation at the beginning and end of the school year during their 6 years of high school and rate the level on a 5-point Likert scale (0: completely demotivated, 1: fairly demotivated, 2: a bit motivated, 3: fairly motivated, 4: completely motivated). They were also asked to write why their motivation became higher or lower. The two research questions posed for this study were “When do Japanese learners of English experience motivators and demotivators in their six years of study in high schools?” and “What are motivators and demotivators experienced during those times?” Through an analysis of the changes in motivation, it was found that the level of participants’ motivation generally went down from the end of the 1st year of junior high school to the beginning of the 2nd year, from the end of the 3rd year of junior high to the 1st year of high school, and from the beginning of the 1st year of senior high school to the end of that school year. The level of motivation generally went up from the end of the 2nd year of senior high school to the beginning of the 3rd year and from the beginning of the 3rd year to the end of that school year. Statistical significance was found between each pair (Bonferroni-adjusted significance level α = .0045). These findings confirm those of previous studies (Hayashi, 2005; Miura, 2010; Sawyer, 2007) which reported the general pattern of the motivational fluctuation of Japanese English learners. Apparently, goals such as success in entrance examinations for senior high schools and universities may be reasonable motivators for many Japanese learners of English. After achieving entrance to junior high school or senior high school, participants may have difficulty adjusting to the class instruction and find it demotivating for a while. Furthermore, it was found that various factors such as experiences of failure, teacher behavior, or the content of classes can be motivators or demotivators. By using reflective surveys, we were able to glimpse the complexities of learners’ motivation. Based on the findings from this study, we discuss the importance of reflecting on our daily teaching practice and call for research considering learners’ contexts in depth.