The Osaka Occupational Health Promotion Center provides information regarding the “Guide of Mental Health Professionals for Workers in Osaka,”, which gives psychiatric specialists in Osaka support for mental health promotion at work and return-to-work programs. The present study sought to reveal factors influencing mental health promotion at work associated with utilization of the guide. We sent 1,249 companies in Osaka a survey about their experience of utilizing the guide, and 369 responded. We contacted 336 companies that had never used the guide, and 214 returned the survey (response rate = 63.9%), while 208 companies that completed the survey regarding their trial use were analyzed. The results revealed that 113 companies used the guide, while 95 did not. Public health nursing, cooperation with managers, training and seminars at work, cooperation with family, and occupational care for return-to-work were associated with increased utilization of the guide. Specifically, public health nursing was associated with an increase in utilization (OR = 2.34, 95% CI: 1.02–5.39), and less cooperation with managers was associated with reduced utilization (OR = 0.22, 95% CI: 0.07–0.65). These results suggest that the Occupational Health Promotion Center should target public health nurses to provide information for promoting mental health at work.