The objective of this research was to investigating the application of Quest-based Learning (QBL) in teaching writing. This research conducted a pre-experimental research. In this research there were two variables, there were independent variable (Quest-based learning) and dependent variable (writing in terms of content and vocabulary). Population of this research consisted of 30 students. This research instrument applied a testwhich used pre-test and post-test. Mean score of the pre-test in this research in content was 74.1 was greater than posttest 69.1. While the mean score of the pre-test in vocabulary was 72.7 was lower than posttest 76.3. From t-test, the study found that the value of t-test in content 4,47 was greater than t-table 2,045 and the value of t-test in vocabulary 9,66 was greater than t-table 2,045.The hypothesis H0 was rejected and H1 was accepted in this research. The findings of this research were indicated that applying Quest-based Learning (QBL) in teaching writing in terms of content and vocabulary was effective.