The purposes of this study were to compare interaction and predict power of psychosocial factors affecting instructors’ behavior with biosocial characteristics. The subjects comprised 300 instructors at Rajamangala University of Technology Phra Nakhon during the 2nd semester of 2009 academic year. Questionnaires were used in this research. Data were analyzed and presented by percentage mean standard deviation analysis of variance Scheffe’ Method and Stepwise Multiple Regression Analysis. The results revealed that Instructors with high behavior as a principle of the sufficiency economy philosophy were instructors with high work socialization and achievement motive and with high group of psycho-social factors. Most of them were female instructors. Moreover instructors’ behavior as a principle of the sufficiency economy philosophy were predicted by work socialization self-ability perception according to a principle of the sufficiency economy philosophy and achievement motive