The atmosphere of the school is important for promoting teachers participation in teachers instructional improvement activities. In this study, we pay attention to the school vitality as the atmosphere of such a school and analyze the effect of school vitality on the teachers instructional improvement activities. The fourth year teacher data of Gyeonggi Educational Panel Study was used for analysis. In order to verify the effect of school vitality on teachers instructional improvement activities, we controlled the teacher-level variables and the school-level variables that influence teachers instructional improvement activities, analyzed through previous researches and then analyzed them with the hierarchical linear model (HLM). The main results are as follows. First, as a result of analyzing the basic model of the hierarchical linear model with the teachers instructional improvement activities as the dependent variable, the difference of the teachers instructional improvement activities between schools was verified. This implies that the school characteristics have an effect on teachers instructional improvement activities. Second, it was confirmed that school vitality had a statistically significant effect on teachers instructional improvement activities. The results of this study suggest that the efforts of schools which expedite collaborative atmosphere would be important in promoting teachers instructional improvement activities.