This research discusses the difference between using paper dictionary and electronic dictionary in students’ idiom comprehension at the Fourth Semester English Department Students in Walisongo State Islamic University of Semarang in The Academic Year of 2018/2019. The method used in this research is quantitative research and comparative study design. The writer used two instruments; questionnaire and test. From the questionnaire, it is known that students prefer electronic dictionary to paper dictionary. Conversely, the result of the test showed that the score of students using paper dictionary (Class A) is higher than the score of students using electronic dictionary (Class C). The score of students using paper dictionary (Class A) is 7, while the students using electronic dictionary (Class C) is 5. It showed that there was significance different between using paper dictionary and electronic dictionary on students’ idiom mastery. Based on the result of this research, the writer suggests the students to use dictionary in comprehending idiom.