Purpose: Grounded on Self-Determination Theory(Deci & Ryan, 2000), the aim of this study was to investigate the longitudinal effect of the autonomy-supportive intervention program on student amotivation in the physical education (PE) context. Methods: In the experimentally-based, longitudinal research design, one-hundred twelve students from four classes of two PE teachers were randomly assigned into either the experimental group(n=50) or the control group(n=62). The questionnaires were administered at beginning (Time 1, T1) of and at middle (T2) of the semester. Repeated measure two-way ANOVAs were used to investigate the effects of need-supportive motivating style on student classroom amotivation and academic achievement. Results: As results, students of the teacher in the experimental group showed greater psychological need satisfaction and less PE-specific amotivation-low ability, low effort, unappealing task characteristics, low value, and problematic relationship than did students of the teacher in the control group. Conclusion: These findings showed autonomy-supportive intervention program to prevent students from being amotivated in PE was effective for the teacher to reduce students’ PE-specific amotivation because the teacher could successfully identify, nurture, and develop students’ psychological needs in an autonomy-supportive way.