The study is held at the twelfth grade students of SMAN 2 Tambun, Bekasi. The objective of the study is to identify and classify the types of error and students sources of errors in writing skill. In order to accomplish the objective of the study, 20 students in the seventh grade are choosen as the sample from the population of 35 students. The method is used in this study is a descriptive analytical method. The writer administers a guide test on descriptive writing. Moreover, to differentiate errors and mistakes, the writer asks the students do the same test on different day on the second day. The students tries to correct the mistakes which have been underlined by the writer. Thus, the error is the students mistake which can not be corrected by the students. After getting the data, the writer analyzed the errors and categories based on grammar error. The study shows that the most typical errors done by the students are in word choice category. The percentage of add a word 20.37% and the writer found that the students made this error because they have not enough vocabulary and knowledge in English language. Then, the second and the third errors done by the students are errors in word choice and omit a word with 18.52% and 16.67%. The errors happened because the lack of their knowledge. It can be concluded that the errors occurs because of the interlingual transfer.