The objective of this research is to compare the health-related physical fitness between before and after using a Social Cognitive Theory-base physical activity promotion intervention of the industrial workers. The samples of research were 50 industrial workers, all workers are in Mahasarakham Province by volunteer selection. The research tool is Social Cognitive Theory-base physical activity promotion intervention, that is suitable for a good level and the content validity was 0.73, Fitness test. The statistical analysis for compare before and after was Wilcoxon Signed Rank Test, which calculated in the program. The results of a Social Cognitive Theory-base physical activity promotion intervention after using the program, the average of skinfold thickness is lower than before using the program with statistical significance at the level of.01 in the relatively thin criteria. And the strength of the arm and hand muscles were higher than before using the program with statistical significance at the level of.01 in the low to medium criteria. As for the cardio-respiratory systems, the mean after using the program was lower than before with statistical significance at the level of .05 in the low criteria. The strength and endurance of leg muscles and the flexibility before and after using the program were not significant. The overall satisfaction of the program is at a moderate level, which some activity in the program such as inviting friends to do physical activities after work can’t do it because of work is late and there is a need for leaders who specialize in physical activity.