The effective teacher has crucial factor in guining the students’ academic achievement in school. Their qualification in teaching can guide the students to have better result in learning. This research is aimed at investigating the effective English teacher and students’ academic achievement. This research also aimed to find out the correlation between effective English teacher and students’ academic achievement at a private junior high school in Yogyakarta. The study applied a quantitative research design. A questionnaire was used for data collection. The data were obtained from 143 students who involved in responding the questionnaire and got academic achievement (report card value). The data were analyzed using descriptive statistic and Pearson Product Moment Correlation (r). The result revealed that the effective English teacher at one of junior high school in Yogyakarta was in moderate level (146.4), and students’ academic achievement (report card value) was in moderate level (78.16). The result showed that the significance value was 0.061 > 0.05. Therefore, the alternative hypothesis (Ha) was rejected because the significant value of the research is more than 0.05. It means that there is no correlation between effective English teacher and students’ academic achievement. It can be concluded that the effective English teacher is not the only noble factors determining students’ academic achievement.