Marx is a philosopher, the same is a social theorist. The beginning of Marx’s social theory is from the person in the social action. All round development of person is the based essentials and incarnation of social development. The reality of social development is regularly through social change. There are inner laws in social change. There is philosophical foundation in Marx’s theory of social change. The foundation is Marxist philosophy, just as dialectical materialism monism, in Marxist theory. The philosophy is historical materialism when it is used in social and history, especially is scientific realism in modern philosophy.