This study examined the effect of the Protestant work ethic on burnout using a sample of 259 South Korean workers from a manufacturing firm. We also investigated the mediating role of emotional dissonance on this effect and addressed the moderating and moderated mediating roles of negative emotion regulation on the relationship between Protestant work ethic and emotional dissonance. Our empirical results indicated a significant direct negative effect of the Protestant work ethic on burnout, but there was no evidence of an indirect relationship between these. Results also found that negative emotion regulation changed the relationship between Protestant work ethic and emotional dissonance. In addition, negative emotion regulation changed the mediating role of emotional dissonance in the relationship between Protestant work ethic and burnout. The study is meaningful in that it grasped the importance of value as a major factor in job burnout, and it finally confirmed the antecedents of Koreans’ diligence.