This study was conducted to investigate the relationship between self efficacy and a health locus of control. We conveniently sampled 204 university students who smoke. We invastigated by using questionaries and collected data that were analyzed using a t - test, an analysis of variance, a Pearson product-moment correlation. The results are as follows: 1. The average score of self efficacy was 66.16 (out of a total score of 100.00) in university students who smoke. In relation to the health locus of control, the internality score was highest at 25.22, the influence of others was 20.39, and the effect of chance was 15.86. 2. In a significant test of the general character other and aspect related to the smoking of the subjects and in the score of the health locus of control, the internality score of subjects who had been never been asked to quit smoking was higher than that of subjects who had been. There are significant differences in the scores concerning the influence of powerful others, especially religion. In chance occurrences, the score of subjects in medical school was higher than in other schools. The lower the age one beginns smoking, the higher the score of chance. 3. In a significant test of the general character and other aspects related to smoking and the score of self efficacy, there was no significant relationship. 4. Considering the relation of self efficacy to a health locus of control, a positive relationship between self efficacy and internality, and the influence of others, but not between self efficacy and the effect of chance. With these results, we can conclude that the higher the level of self efficacy, the higher the internality, the higher the influence of powerful others. Consequently, it is necessary to identify the relationships clearly among self efficacy the health locus of control by repeated research. It can be used to support, revise and develop health behavior theory.