Changes in airport and airline employment patterns were caused by the development of airline transportation and competition in the airline service industry. In an unstable employment environment, such as outsourcing and non-regular jobs, the concept of job stress, job instability, and depression must be important issues for workers who perform a high level of emotional labor. The purpose of this study was to examine the relationship between job stress, job instability, and depression among workers in the airline service industry who had direct contact with customers, as well as the effect of positive psychological capital as a moderating variable for prevention and treatment. An online survey of workers in the domestic airline service industry was conducted for this purpose, and 222 valid samples were obtained. Factor analysis and regression analysis were used to investigate the relationship between job stress, job instability, depression, and positive psychological capital. The study's findings are as follows. For starters, there was a statistically significant link between job stress, job insecurity, and depression. Job stress had an effect on both job insecurity and depression. Second, job insecurity had a negative impact on depression. Third, as a moderating variable, positive psychological capital was found to have an effect on job stress, job instability, and depression. This study discovered that job stress had an impact on job instability and depression among airline workers. The outcome can be used to detect job stress and improve employee mental health. Employees in the airline service industry may experience job stress, job insecurity, and depression, which can have a negative impact on corporate performance. As a result, in order to reduce workers' negative psychological status, airlines must apply the concept of positive psychological capital to manpower management.