Introduction: There is no objective measurement of physical activity and sedentary behaviour for high school stu- dents, especially student-athletes who registered in sport specific class in Indonesia. The purpose of the study was to investigate physical activity and sedentary behaviour using objective measures with ActivPal. Methods: A total of 36 high school students (17 Male; 19 Females) participated in the study. Participants wore an ActivPAL™ on the right tight for seven days to determine light and moderate to vigorous physical activity stepping and the total sedentary time (lying and sitting). Results: : The high school students who took a sports specific class spend the average time for moderate to vigorous physical activity 2,08 hours, sitting time 9,33 hours, primary lying 8,5 hours, and secondary lying 1,24 hours every day. There is no difference in the time used for physical activity and secondary lying between males and females (p > 0.05). Meanwhile, male, and female students’ sitting, and primary lying times were signifi- cantly different (p < 0.05). Conclusion: Male students spend more sitting time, and females spend more primary lying time. Almost half of the day, high school students in special sports classes are paid for sedentary activities, and their daily physical activities still do not meet WHO recommendations.