This paper aims at clarifying some traits in Kurauchi's sociological theory and pointing out its uniqueness or high theoretical level. To do so I take up a problem of society as a whole in contrasting with Luhmann's societal theory. And then, I choose the following three topics, the definition of concept of society as a whole, social differentiation and social change.
Though it is the most difficult task to bring out a general proposition, we cannot avoid this problem. The investigation of the problem is carried out in which destiny, stream, rule, and norm constitute.
The social differentiation is characterized by forms of segmentation, stratification, and functional differentiation. Using this triadic typology and three grouptypes that is befor group, neal-group, and after-group as factor of structural change give explanation to the change of societal system.