Abstarct: The purpose of this study was to evaluate the relationship between coaching efficacy with sport commitment among volleyball plaxyers of semnan province. The statistical sample were 250 members of volleyball teams in semnan province that have at least two years sport experience. The research instruments were consists of Coaching Efficacy(Feltz,1999) and Scanlan and Colleagues,1993 Sport Commitment Questionnaires (SCQ). In order to determine validity of the questionnaires used physical education proffesores and experts comments and their reliability determined by cronbach΄s alpha, α= 0.96 (CEQ) and α= 0.57 (SCQ) in a pilot study.. K-S test showed a normal distribution, except of strategy efficacy subscale. So the data were analysed using Pearson and Spearman coefficients, independent t-test, one way ANOVA and linear regression. The results showed a significant positive correlation between perception of coaching efficacy and it΄s dimensions (motivation, strategy, technique, character building) with sport commitment. Also coaching efficacy and sport commitment differed significantly on the baxse of sex. But there was not significantly differente between of perception of coaching efficacy with championship and sport activity history. Perception of character building efficacy forecast the sport commitment. Finally, we conclud that athletes perception from coaching efficacy, especially in character building dimension has positive correlation with sport commitment. So these results emphasize the importance of athletes perception, using suitable and moral behaviors by coaches and notice to select efficient coaches for increasing athletes commitment