This Thesis discussed the influence of students’ dictionary use towards their affix comprehension. This research is to find out students’ dictionary use, students’ Affix comprehension and The Influence of students’ dictionary use towards their Affix comprehension. This research is a quantitative research type, which specified in regression. The population of this research was EFL Class of SMA N 12 Semarang. The total population of the study was 63 students grouped into two classes. The data were collected through Test and Questionnaire and were analyzed using Regression. In this research, the degree of student’s dictionary use was 58.2. It means that the category of student’s dictionary use was quite. The degree of students’ Affix comprehension was 56.6. It means that the category of the students’ Affix comprehension was medium. it was found that there was a significant influence between students’ Dictionary use and students’ affix comprehension. It could be seen from Regression result was Freg> Ftable, that was 44.289> 3.99 and Y= 19.62+0.635X. It meant that students’ dictionary use had affected students’ Affix comprehension. Therefore the hypothesis was accepted. It means that there was quite influence of dictionary use towards their Affix comprehension. From this research, the researcher suggests that teachers have to explain Affix from the word and teach students in choosing word exact on dictionary, the school institution should support teachers to create enjoyable learning, and teacher should be innovative in teaching learning process.