Some lecturers at English Education Department of Universitas Muhammadiyah Yogyakarta complained that many students of EED of UMY lacked mastery of passive voice mastery. This matter made the researcher interested in conducting the research. This research aimed to find out the students’ mastery of passive voice at English Education Department of Universitas Muhammadiyah Yogyakarta. This research used quantitative method with quantitative descriptive design. In addition, this research took place at English Education Department of Universitas Muhammadiyah Yogyakarta by involving 108 students batch 2014 as the participants. To collect the data, the researcher used a grammar test as the instrument. The test consisted of 20 questions that were divided into 10 dichotomous questions and 10 multiple choices questions. The result showed that the mean score of the students’ grade was 63.06 % meaning that their mastery level of passive voice was in ‘fair’ category.