This study aims to understand children`s aggressive behaviors which have established the sources of serious problems such as school violences and self-injured actions, and to give fundamental informations which are helpful to the effective remediation of the aggressive behaviors. So, some students of 4th, 5th, and 6th grade of an elementary school are selected as a group of subjects. This study is focused on how the subject group did aggressive actions under the actual and specific range of social circumstance of `school`, and the types of such actions. Thus researchers used ethnographic study - the way of describing everyday lives - that They might accomplish the aim of this study well. The method is to deeply concern with a peculiar social culture, school, and to collect and analyze necessary data. Findings show the types of children`s violent behaviors, especially some that need one`s attention. These are as follows : First, one of motives of aggressive actions is that a simple mischief with no intention and hostility leads to an aggressive action. Second, some students use aggressive actions which seem to be the signs of school violence in order that they may prevent others` aggressive actions and punish them. In the process of showing the aggressive characteristic : 1) even if it is not serious, some students used knives and scissors to others, 2) Some students used the way of biting others like animals. It is also shown in findings that these aggressive actions give much emotional influence to witnesses of same age as well as aggressors and victims, and cause them to learn aggressive behaviors through thinking process, negative of positive.