The purpose of this investigation was to determine the effect of physical activity program on body composition and cardiovascular risk factors in security guards. The subjects consisted of twenty security guards who are working to the security company in Seoul, physical activity group of 10 people and control group of 10 people in 2012. The results were as following. For body composition, there were significant decreases in body fat, also significant increases in fat free mass(p<.05). There were significant decreases in TG, elevated HDL-C was observed with physical activity group(p<.05). It is concluded that physical activity program might make beneficial effect such as increasing fat free mass, it also produces lower incidence of cardiovascular disease during 12 weeks in security guards.