English has been studied for many years and it is very important to know syntactical errors produced because it gives the information about the factor affect the language errors and helps to improve teaching and learning strategies for the English language. This study aimed to investigate the syntactical ability in writing English text. 25 students were the participants of the study namely students of the third and fifth semester of the English Education Department in Musamus University. This study is a mix-method. Quantitative was used to see the percentage of grade error committed by students after that conclude quantitatively. The focuses of syntactical analysis were noun, verb, adjective, auxiliary, determiner, noun phrase, verb phrase, dan the students’ ability in making tree diagram. Based on the result, most students can decide the word class but in phrase term, most of the students are still confused to differentiate between a noun phrase and adjective phrase. Moreover, most students still difficulty in making tree diagrams in syntactical analysis.