Demotivation is a relatively new issue in the field of second language (L2) motivation. In this study, we review previous studies that investigated demotivation of learners of English in order to identify common demotivating factors and report a survey study which explored demotivating factors for Japanese high school students. A 35-item questionnaire was completed by 656 Japanese high school students. Through a principal axis factor analysis, five demotivation factors were extracted: (a) Learning Contents and Materials, (b) Teachers' Competence and Teaching Styles, (c) Inadequate School Facilities, (d) Lack of Intrinsic Motivation, and (e) Test Scores. The results showed that the Learning Contents and Materials and Test Scores factors were demotivating factors for many Japanese high school students, especially for less motivated learners. Contrary to what previous research suggested, Teachers' Competence and Teaching Styles was not a very strong cause of demotivation compared to Learning Contents and Materials or Test Scores for both more and less motivated groups. This study also showed that both more and less motivated learners did not perceive Inadequate School Facilities as demotivating. (Contains 6 tables and 1 figure.)