The goal of this study is to show the relevance of organizational justice principles in interventions to prevent psychosocial risks. Following an introduction identifying organizational justice as a predictor of health and quality of work life, we illustrate its application to a diagnosis and an intervention for hospital staff. The responses of 685 employees to a questionnaire identified a lack of support and justice by managers; thus, sensitivity to organizational justice was incorporated into a training program on management and psychosocial risks. A quasi-experiment in which hospital staff participated revealed a beneficial effect of the manager training on justice perceptions of the staff, confirming in part our hypotheses. The illustration in our study of the benefits of using justice principles in manager training offers new perspectives for promoting quality of life at work and reducing psychosocial risks.