The purpose of this study was to examine the effect of a semester of physical education class on Japanese college freshmen（N = 322）by applying the concept of “Physical Activity Pyramid”（Corbin & Lindsey，1997）and behavior change skills to their physical activity level. The control group（N = 156）attended a class that included “two health−related physical fitness tests,” “one lecture,” and “nine sports activities.” In addition，the intervention group（N = 166）attended the class that included a physical activity enhancement program that comprised “Learning of the concept of the Physical Activity Pyramid,” “Worksheet practice of behavior change skills,” and “Monitoring of physical activities in daily life.” The number of steps per day to be implemented were changed before and after attending the class（control group 7841 ± 2965 - 7693 ± 2781 [-1.9%]，intervention group 7890 ± 2821 - 8546 ± 2861 [+8.3%]). The results of ANOVA revealed that the number of steps implemented per day in the intervention group increased as compared with those implemented in the control group. This increase in the number of steps in the intervention group occurred on a holiday rather than on a weekday. An examination of the physical activity pattern before and after attending the class，and at the follow−up period using the Physical Activity Assessment Scale（PAAS; Wakui & Suzuki，1997）indicated that there was no significant difference in the measures of the relatively light physical activities in daily life，i.e., “Daily Activity” during each measurement time. On the other hand，in measures exercise/sports−related physical activities with more than moderate intensity “Exercise/Sports”，the intervention group had significantly higher point than the control group after attending a class. However，with regard to the scores related to “Exercise/Sports,” there was no significant difference between the two groups during the follow−up period（three months following the completion of the class)．In conclusion，it is apparent that a physical education class that included the concept of Physical Activity Pyramid and behavior change skills enhances physical activity among Japanese college freshmen for the period of attending the class.