Speaking anxiety is the state when the learner feel worry, stress, and uncomfortable to speak English with others. Speaking anxiety can happen to any of student due to lack of English knowledge, communication apprehension, and afraid of making mistake. This study aimed to investigate the causes that contribute to speaking anxiety as well as the strategies to regulate speaking anxiety used by senior high school students. The participants for this research are six students, with four students of the twelfth grade and two students of eleventh grade from one of Islamic private senior high school in Yogyakarta academic year 2019/2020. The participants were selected using purposive sampling. The results of this study revealed that the students experience anxious feeling when they need to speak English with each other that caused by these following factors: communication apprehension, test anxiety, and fear of negative evaluations. Further, the research also found that the students have strategies to regulate their anxiety. These strategies are: preparations, relaxation, positive thinking, peer support, resignation, and teacher support.