The purpose of this study was to investigate the effects of athletic identity on exercise behavior within the Theory of Planned Behavior. By purposive sampling, the samples were members of sports club at junior and senior high schools in Taiwan. The total sampling number of the study was 220 with 205 valid questionnaires; the effective response rate was 97.6%. The analysis of collected data was undertaken by performing Structural Equation Modeling (SEM) with AMOS19.0. The results indicate; 1) subjective norm does not have a significant influence on behavioral intention; 2) Attitude has a significant influence on behavioral intention; 3) perceived behavioral control does not have a significant influence on behavioral intention; 4) perceived behavioral control has a significant influence on behavior; 5) athletic identity does not have a significant influence on behavioral intention; 6) athletic identity does not have a significant influence on behavior; 7) behavioral intention has a significant influence on behavior.