This study aimed to understand the job satisfaction and work-life balance (WLB) of registered dieticians and dieticians working in large-sized hospitals. Our analysis was based on a questionnaire survey administered to 185 participants at 39 hospitals with 400 or more beds in the Kanto and Kansai regions. Participants exhibited an overall general state of well-being. Although the content and quantity of their work were regarded as burdensome to some extent and could be improved, their relationships with colleagues and patients were generally positive, and their work made use of their abilities. The median job satisfaction level was 70.0 [interquartile range (IQR) 50.0-80.0] points out of 100 points, and the most influential item in the multiple regression analysis was “level of WLB.” The median WLB satisfaction level was 60.0 (IQR 33.8-80.0) points out of 100 points, and the most influential item was “level of job satisfaction.” Our results indicated a mutually influential relationship between the job satisfaction level and WLB satisfaction level.