Short sleep duration is a serious problem that not only enhances the risk of various mental and physical disorders, but also affects the productivity in the workplace. However, in terms of studies focused on workers, there are few reports that evaluated sleeping conditions in an objective way. The purpose of this study is to implement sleep health education in the workplace in terms of primary prevention of mental health disorder and then to investigate the subjective and objective effectiveness of the education using self-administered questionnaires (sleep duration, ESS, AIS, PHQ-9, SF-8) and an activity monitor (MTN-210). Study design is a quasi-randomized controlled trial. Sleep health education was provided through three 50-min lectures (total 150 min) as a single cycle for five months in the Intervention group. We obtained baseline data and then six months later. The study analyzed 70 subjects (36 Intervention group, 34 Control group). The weekday sleep duration for the Control group decreased by 12.9 min, whereas that of the Intervention group increased by 14.3 min (difference of 27.2 min), resulting in a significantly increase in score for the Intervention group. The present study suggests that sleep health education may be beneficial for good sleep habits in workers.