Philosophical issues about reductionism in philosophy of science are started from Logical empiricism. The reduction model that is started from Nagel is provided the frame of reductionism;;s argument. The reduction model as a deductive derivation could have been a good basis that science could make progress continuously. However the criticism of Kuhn and Feyerabend that reduction of Nagel never happened in the history of science is enough to modify the reduction model. Although the modification is reached the general reduction model, Schaffner has come to the situation that he has to acknowledge it is a only perfect model as a kind of regulative role. Meanwhile, the reduction model as a deductive derivation needed other models about reduction in life science, because the reduction model is based on nomological theories. It is good to adopt the frame of mechanistic explanation, because life science aims to find mechanism, not aims to find nomological theory. In mechanistic reductionism, there are three important issues.