Partnership commitment is identifies as the key success factor contributing to the success of SME IJV performance. Based on the set of inter-partner relational factors in past research studies, commitment has become an important and outstanding relational factor influencing the success or failure of IJV firms. A mismatch of partnership commitment, disproportionate commitment may leads to conflict between partners, erode of partner relationship and eventually leading IJV partner’s dissatisfaction and dissolution. Thus, the objective of this study is focus on partnership commitment as the mediating effect between market orientation (MO) and SME IJV performance. The results show the highly positive significant relationship between MO and SME IJV performance. This finding indicated the important of commitment which refers to partners duties in IJV firms and letter is Japanese and Thai partners are perform their responsible based on their duties. Through IJV partnership commitment, Japanese and Thai partners are able to clarify their duties and later both partners are cooperated to achieve of IJV’s target goal and objectives. As of this point, the successful of Japanese-Thai SME IJV firms can ensure by IJV partnership commitment.