Alfiana Kewa Madja Pengarang Alexander Home Kabelen Dosen Pembimbing 1 Merlyn K. Nelloe Dosen Pembimbing 2 Alexander Home Kabelen Penguji 1 Gracia M. N. Otta Ketua Penguji Merlyn K. Nelloe Penguji 2

The aims of this study are to find out the errors made by the students in changing active voice to passive voice; and to find out the problems faced by the students in changing active to passive voice. This study used descriptive qualitative method. It was conducted in the eleventh graders of SMAN 1 Larantuka. The data of this research was 22 students from science class. The research instruments used for data collection were a test, an interview, and documentation. The test was distributed to the students to analyse their errors. The total of students’ error in changing active voice to passive voice is 152 errors. Which is divided into 4 (2,63%) errors of addition, 45 (29,60%) errors of omission, 78 (51,31%) errors of misformation, and 25 (16,44%) errors of misordering. The interview result was used to get qualitative data to answer the second research question. The difficulties encountered by the eleventh graders of SMAN 1 Larantuka were determine pronouns, using auxiliary “be”, and using past participle. Keywords: error analysis, problems, passive voice