. This research examined longitudinal trajectories of Korean students' motivation to learn science using groupbased trajectory modeling (GBTM). The changes in five motivational constructs were focused in this research: self-efficacy, intrinsic motivation, grade motivation, self-determination, and career motivation. In addition, the relationship between academic track of students and each trajectory group was examined. Using Science Motivation Questionnaire II, data from 255 male high school students were collected during five semesters. Longitudinal data were analyzed by GBTM.. Chi-square analysis was also conducted to examine the relationships between academic track and each trajectory. As a result, it was found that students shared the same trajectory patterns in self-efficacy. Otherwise, two distinct trajectory groups ('high' and 'low') were found in each four constructs. There were significant correlations between academic track and trajectory groups. The findings of this research suggest that Korean science educators need to consider individual student's longitudinal trajectory of motivation to provide better science teaching and learning.