This research aims to analyse the efforts of the character building of school culture based in Senior High School of Panca Budi Medan as well as supporting factors and the termination. This research uses qualitative method with the research site, namely Senior High School of Panca Budi Medan. As for the data analysis techniques using interactive analysis Model Milles & Huberman is through data reduction, data display and data verification/withdrawal conclusion. Determination of the subject using snowball sampling technique. Data collection techniques using non-participatory observation, in-depth interviews and documentation studies. From the results of the study obtained a number of schools culture that became the frame and base of character formation of students in Senior High School of Panca Budi Medan, namely; 1) Religious culture, 2) honest culture, 3) clean culture and energy saving, 4) Culture of discipline. The supporting factor for student character formation in Senior High School of Panca Budi is 1) family factors that emphasize the role of parents in strengthening the habituation of good behavior to the child of what results have been received in school; 2) The teacher's factors emphasize the teacher's involvement in shaping the student's character through education, mentoring, and the example; 3) environmental factors that include the school environment and community. In supporting the character building of the students, the school constantly engineered a conducive environment so that what the students see, hear, and feel are supportive of character building. The Community's environmental support is seen from conduciveness the daily behaviour of local residents in line with the values of characters obtained by students from the school; 4) Learners ' factors that appear to be high in enthusiasm and curiosity in understanding the importance of character value inherent in every activity that cultures in school..........................