The purpose of the present study is to evaluate the effects of Mental Fitness Positive Psychology; MFPP) program for improvement of adjustment to military life. In the present study, the Mental Fitness program (Kim & Ko, 2009) was adapted for the Korean Army. A total of 78 military soldiers were divided into two groups: the MFPP group (n=35) and control group (n=43). The results of the present study are as follows: relative to the comparison group, the MFPP group showed a significant decrease of military life stress and a significant improvement of adjustment to military life. These results suggest that, in spite of a short-term intervention consisting of 6 weekly sessions, the MFPP program adapted for military soldiers was effective in enhancing soldiers' adjustment to military life. Lastly, the implications of the present study and directions for future research were addressed.