This study examined the effect of internal capabilities of the domestic aircraft manufacturing companies on sustainable competitive advantage(SCA). Specifically, this study suggested technological competence(TC), product competence(PC) and managerial competence(MC) as internal capabilities of the domestic aircraft manufacturing companies. Furthermore this study investigated the mediating effect of market orientation(MO) on the relationship between internal capabilities of a company and SCA. As a result of analysis using a structural equation model based on data collected from employees of domestic aircraft manufacturing companies, it was found that technological competence and managerial competence have a direct positive effect on SCA, but product competence does not have a direct positive effect on SCA. It was also found that all three competences of technological competence, product competence and managerial competence have a positive effect on market orientation, and market orientation has a positive effect on SCA. Finally, it was found that market orientation has a positive mediating effect on the relationships between three internal capabilities of domestic aircraft manufacturing companies and SCA. The results of this study have theoretical implications in that it found the effect of the internal capabilities of aircraft manufacturing companies on SCA and that it found the mediating effect of market orientation on ths relationship between the internal capabilities of aircraft manufacturing companies and SCA. In practice, this study suggests that domestic aircraft manufacturers should focus on developing their internal capabilities in order to achieve MO and secure a SCA.