The purpose of this qualitative single-case study is to examine the current level of motivation and the demotivational reasoning of a Turkish EFL teacher working at a secondary school in the secondary service area in Turkey. The data were collected from three sources for triangulation: a) interview, b) self-reflection papers, and c) a diary kept by the participant. The study lasted 14 weeks. The analysis was based on pattern matching. The findings showed that lack of self-motivation is the most frequently stated issue that causes demotivation. Further, the study showed that extrinsic factors (e.g. curriculum and course book, facilities for teachers, and school administration) can negatively affect the demotivation of the EFL teacher.