The purpose of this study was to investigate the effect of task and relationship conflict on job burnout and the moderating effects of achievement motivation of engineers in plant design and engineering division. To study this investigation, 483 questionnaires were collected from the staff in big and medium size engineering companies in Seoul. The result of this study was summarized as below; Firstly, task and relationship conflicts have positive relationship on emotional exhaustion and cynicism. Secondly, relationship conflicts have negative relationship on reduction of accomplishment but task conflicts showed no relation on it. Thirdly, interaction effects of task and relationship conflict, and achievement motivation showed significant moderating effects on job burnout partially. In conclusion, conflicts were identified as significant predictor variable on job burnout and achievement motivation showed the moderating effects partially. Accordingly, as per meaningful results of this study, it was proposed ideas to utilize these results in counseling for prevention of job burnout.