The aims of the research were: (1) to find out how high is the
students’habit in using smartphone, (2) to find out how good is the students’
vocabulary mastery, (3) to find out whether or not there is a correlation between
students’ habit in using smartphone and their vocabulary mastery. The sample of
this research was 40 students. The data were collected through questionnaire and
test. Questionnaire is a number of questions which are used to measure students’
habit in using smart phone, while test is sequence of questions which are used to
measure students’ vocabulary mastery. The data were analyzed by using
descriptive correlation study. The writer took the data on 15 June 2015 at the
Second Semester Students of English Education Department of Muhammadiyah
University of Purwokerto. After the data had been analyzed, it was found that
there was a significant correlation between students’ habit in using smartphone
and their vocabulary mastery. It could be seen from the result of product moment
computation where rxy obtained 0.367, the r table for N = 40 at the level of
significance 5% was 0.312. So the result of rxywas higher than r table. In
conclusion, the students who have good habit in using smartphone also have good
vocabulary mastery.