Dictionary is useful tool for language students if they use it effectively. In English Language Education Department in one of the private university in Yogyakarta, most of lecturers recommend their students to use printed dictionary to aid them in understanding English textbook yet almost all the students choose to use electronic dictionary (ED) because of the convenience offered. The purposes of this research are to discover the advantages and to find out the disadvantages perceived by students while using electronic dictionary in understanding English textbook. This research use interview to gather the data needed for the completion of this study. The interviews revealed that the result have seven categories on the advantages. They are electronic dictionary comes in handy, students can improve pronunciation by copying the sound from the device, students know how to put a word in a sentence by looking at the examples provided by electronic dictionary, electronic dictionary saves a lot of time, electronic dictionary eases students to look up the words needed, electronic dictionary can promotes autonomous learning, ED is easily modified to add more words or phrases. For the disadvantages, there are two categories, which are electronic dictionary makes students lazy to memorize, and electronic dictionary easily distracts students’focus in classroom activities. In Conclusion, both dictionaries will be useful for the user if the user knows which dictionary to choose for their needs and how to use it effectively.