Introduction: Many athletes, coaches, and sport psychologists have long recognized the importance of mental toughness in terms of progressing and being successful in sport. Key components of mental toughness include Control, challenge, commitment and confidence. Commitment is one of the important components of mental toughness that shows an athlete being deeply involved with pursuing goals and striving to achieve them despite difficulties. Therefore, this study aimed to investigate the relationship between mental toughness and sport commitment of team and individual athletes. Methodology: The statistical population consisted of 400 athletes of team (football, futsal, volleyball) and individual (boxing and wrestling) sports. The sample consisted 196 athletes who (individual athletes = 70, team athlete = 126) were selected by available sampling. The research instruments for collecting data in this study were questionnaire of Sport Commitment Questionnaire (Scanlan et al., 1993) and Mental Toughness Questionnaire 48 (MTQ48). The validity and reliability of questionnaires was confirmed in previous studies. To analyze data, Kolmogorov-Smirnov test, independent sample t test, Pearson correlation and multivariate regression were used. Results: The findings showed that among components of mental toughness and sport commitment, the control and sport enjoyment components had the highest average respectively. Comparison of mental toughness between team and individual athletes reveled the mental toughness of individual athletes is significantly more than team athletes. Pearson correlation showed that there is a positive and significant relationship between mental toughness and components of sport commitment. Furthermore, the components of mental toughness significantly predicted the sport commitment variable. Discussion: Based on the findings of the study, it was concluded that the development of mental toughness can increase sport commitment of athletes. Therefore, the use of
