Purpose: To determine out the motives of perpetrators of sexual violence against children in the immediate environment and how the modus operandi carried out by the perpetrators. Research Methodology: This type of research is qualitative with a case study approach to 5 perpetrators of sexual violence against children in LPKA Class I Medan. Results: The results of the study indicate that there is superior position and interior between the perpetrator and the victim, where the perpetrator feel more more powerful than victim so that triggering the occurrence of sexual violence. The existence of motive in the past past (because motive) such as the existence of experience bad experience in the past past that causing a sense of resentment and all informants lack get early socialization from their families in the past especially in understanding religion. Motives in the present (in order to motive), namely reasons that delivered by the perpetrator such as discommunication family, promiscuity and frequent watching movies which influence perpetrators commit violence sexual violence. Modus modus operandi in this research is that opportunity becomes one of the one of the factors that can trigger the occurrence of sexual violence sexual violence. Limitations: This research limits the scope of the study to only look at perpetrators based on the motives and modus operandi that led to the occurrence of sexual violence against children and how the background of the perpetrators of child sexual sexual violence against children. Contribution: It is expected to contribute to the development of science in the Department of Social Welfare sociology for social welfare, family sociology for social welfare and social work practice. Adding information about the motives of perpetrators of sexual violence that occur in children and with this research, it is hoped that families can be careful in protecting their children. besides that, it also provides input to related parties, especially the medan city government, class I special child development institutions and the office of women and children empowerment.