One of the language aspect required in translating English text is grammar. In addition to word-choice for example whether or not a product of translation is good can be identified by its grammatical structure of sentences. Wrong or incomplete grammar in writing may sometimes cause readers to get confused in understanding the message. This study aims at analyzing grammatical errors made by students of sixth semester of English Department of Universitas Islam Kadiri academic year 2018, in translating first language (Bahasa Indonesia) into target language (English). The major types of errors made by the students were related to incomplete clauses having no either subject, verbs, or either both, subject-verb agreement and the absence of subordinators and plural nouns. Out of the six types of identified grammatical errors, incomplete plural nouns ranked number one followed by the absence of verb, and subject-verb agreement. The highest number of students making mistakes on using plural nouns was 41 (29%), and the lowest one on the absence of subject and verb was 7(5%). From the error analysis, it could be generalized that the students were probably influenced by their native language system which does not exist in English. Therefore, differences of the language system especially in grammar should be introduced to the students during the translation studies.