The study aimed to examine job characteristics for middle-aged workers using decision tree analysis. To do this, data from the 25th wave of the Korean Labor Panel (year 2022) was utilized, with a study sample 4,570. First, the factor with the most significant impact on employment according to gender was identified as 'work hours format.' When working full-time, the percentage decreased by 36.5% for women and increased by 63.5% for men. For part-time work, the percentage increased significantly by 85.5% for women and decreased by 14.5% for men. Second, the factor with the most significant impact on employment according to age range was identified as 'highest education level.' For those with a high school education or below, the percentage decreased by 38.2% for ages 40-49 and increased by 61.8% for ages 50-59. For those with a college degree or higher, the percentage increased by 66.0% for ages 40-49 and 70.0% for those with an associate degree. Third, summarizing the study results, the proportion of men is higher for individuals with a college degree or higher, working full-time, and having high job satisfaction. On the other hand, the proportion of women is higher for those working part-time and having a high level of welfare benefits. Additionally, for individuals with an associate degree, stable employment, and job satisfaction, the proportion of those in their 40s is higher. For those with a high school education or below, working in non-office jobs, and having unstable employment, the proportion of those in their 50s is higher. Given that middle-aged workers are more likely to withdraw from the labor market as they age, continuous evaluation of educational training and policy support for job sustainability is necessary. There is a need for support to maintain quality employment even after reemployment.