The purpose of this study was to find out whether or not there was effect between students who were taught by using Instagram and conventional media.. Therefore, this study was quantitative research, using experimental method and true experimental design. Then, the population of the study were 90 from three classes. And the technique sampling was chosen by cluster random sampling. There were two groups they were experimental group with 30 students and control group consists 30 students. The writer used written test as an instrument for the collecting the data. The data obtained from Independent t-test analysis, between the result of post-test in experimental group and control group. Based on the calculation by using Independent t-test, the writer found that t _obtained was higher than t _t (3,844 > 2,000) at the significant level α = 0.05 in two tailed test. It meant that there was the effective between experimental group and control group. So, the null hypothesis (Ho) was rejected and alternative hypothesis (Ha) was accepted. It can be concluded that Instagram effective in teaching writing.