This study aims to understand the conditions of job satisfaction and work–life balance (WLB) of registered dieticians and dieticians working in medium-sized hospitals. We based our analysis on a questionnaire survey given to 396 participants (97.5% were nationally registered dieticians) in 152 facilities. Participants worked in medium-sized hospitals and exhibited an overall general state of well-being. Although the content and quantity of their work was regarded as burdensome to some extent and could be improved, relationships with colleagues and patients were generally positive, and their work made use of their abilities. The median value (interquartile range) of job satisfaction level was 70.0 (50.0–80.0)/100 points. The most influential item in the multiple regression analysis was“current work is an opportunity to improve abilities.”The median value (interquartile range) of the satisfaction level of WLB was 60.0(40.0–80.0)/100 points. The most influential item here was “level of job satisfaction.” Our results indicated a mutually-influential relationship between job satisfaction level and WLB satisfaction level.