The purpose of the present study was to investigate the relationship between teachers' leadership behavior, the group power structure of pupil, their solidarities and norms in the classroom. Subjects were 3007 pupils from 83 classrooms of elementary schools. Main results were: (a) Centralizing structure of pupil was found more prevalent when teachers' leadership was strong in the P (Performance)-dimension, and their diffuse structure was found more prevalent when their leadership was weak in the P-dimension. (b) When teachers' leadership was weak both P- and M (Maintenance)-dimensions, the solidarity of the classrooms in terms of the centralizing structure of the pupil was found stronger than that of the diffuse structure.