Purpose: This study aimed to identify the predictors of psychological well-being in middle-aged female workers by examining the relationship between positive psychological capital, job stress, and job satisfaction. Methods: Data were collected from 145 middle-aged female workers. A self-report questionnaire was used to assess the level of positive psychological capital, job stress, job satisfaction, and psychological well-being. SPSS/WIN version 23.0 was employed for data analysis. The data were analyzed using descriptive statistics, t-test, ANOVA, Pearson’s correlation coefficient, and multiple regression. Results: The most significant predictors of psychological well-being in the participants were positive psychological capital, living standards, and hobby. These explained 39% of the variance for psychological well-being. Conclusion: We found that positive psychological capital, living standards, and hobby influenced the participants’ psychological well-being. Therefore, to improve middle-aged female workers’ psychological well-being, developing a program based on positive psychological capital management is necessary.