In this article I have examined the cell theory of T. Schwann and considered whether Schwann is to be called a reductionist. Schwann paid more attention to the development of cells rather than to the structure of them. That was because he intended to establish the unified theory of organisms which can be used to explain the regularity of the development. Schwann assumed the unteleological force of cell development, regarded physical method as the ideal method of science, and used the analogy between cell development and crystal development. But he did not identify organic forces with unorganic forces and intended to certify the unity of organic world. So it is true that Schwann introduced physical method to life science, but reduction of biological theory to physico-chemical theory has little to do with him.