The purpose of this study is knowing the most typical errors done by the second year students of SMK La Tansa Banten. The writer used writing test in guiding this study. To differentiate between errors and mistake, the writer used the students narrative writing in this study. The students did the same test on the different day. The writer collected, corrected, and underlined the mistake of students narrative writing. After getting the data, then the writer analyze the errors based on the grammatical aspects. Based on the study, the most typical error done by the second year students of SMK La Tansa Banten is in verb tense on percentage 17.9 % because most students forgot using the simple past when they wrote narrative writing. The second and the third typical errors done by the students are word choice and capitalization on percentage 16.5 % and 14.2 %. The errors are mostly made because of their lack of grammar rules and lack of knowledge in foreign language learning. It means intralingual transfer and interlingual transfer are the most typical source of errors.