1. School management, which aims at building up creative and autonomous character maintains its relative independence from school administration. Schools have, and must have, therefore, the ability of establishing and maintaining their own order and discipline within themselves. The order and discipline thus established comprise what is called the inner school law (innere Schulrecht) or the school customary law (Schulgewohnheitsrecht). In order to enhance the creativeness of school education and management it is important and essential that this law should be developed so as to contribute to the democratization and rationalization of schools. The present thesis is intended to construct a basic theory for it, especially from the standpoint of the sociology of law. 2. The school customary law presents an excellent norm for school management, and comes closer to educational facts than anything else. It consists of two laws: the customary law of school administration and that of school instruction. Greater emphasis is put on the latter in this thesis. 3. The school customary law must also be a means of school management to have the general demands of the statute laws on education refracted and supplemented positively and individually. 4. Rechtsdogmatik (Jurisprudence) makes a sharp distinction between a customary law as fact and a customary law, while Rechtssoziologie (the sociology of law) treats the two as a continuum. Here the present writer grasps the school customary law from the standpoint of the latter. A criterion "recognition by the statute law", therefore, is not so strictly applied here as in Rechtsdogmatik, The customary law as fact is relatively distinguished as a transitive thing which is to develop into a school customary law as a living law. The character of a school customary law is judged by a criterion whether it is based on the definite consciousness of rights and duties. It can further be said to be the social correlation within and without schools crystalized into objective rules. 5. The analysis of the school customary law from the standpoint of the sociology of law is to be centered on the soial processes of agreement and contradiction between the customary law and the statute law on education. It is not to be directed only toward the processes of agreement. This means that the pre-requisite of the analysis is to grasp the structure of sanction in law as pluralistic. 6. In the study of the school customary law from an angle of the sociology of law which aims at setting up the relative levels of sanction in the system of school management, the discrimination in the relative sense between public and private legal concepts in schools is a problem which remains still unsolved.