The purpose of the present study is to investigate the relationship between teacher efficacy to student trigonometry self-efficacy and student trigonometry achievement. The study included 16 high school teachers and their tenth grade students (n = 571). Teacher efficacy was studied in terms of general teaching efficacy, mathematics teaching efficacy, and trigonometry teaching efficacy. No significant relationship was found between general teaching efficacy or mathematics teaching efficacy and student-related variables. The t-test results show that students of teachers who had high trigonometry teaching efficacy got higher scores on the trigonometry self-efficacy scale, than students of teachers with low trigonometry teaching efficacy. Between these two groups of students' achievement test scores, on the other hand, no significant difference was found. The results underline the importance of teachers' trigonometry teaching efficacy for students' trigonometry self-efficacy, as well as the importance of measuring self-efficacy in a task-specific way.