In general, the molecular target drugs were superior in the effect, less toxic and realized personalized medicine, resulting in progress in the cancer therapy. The rise in development cost of the molecular target drug and a decrease of the development efficiency become the problem of the drug industry recently. As the solution, development of the excellent biomarker associated with the drug development is considered to be the most important issue. Therefore, the development of the companion diagnostic agent which can evaluate the biomarker precisely is prosperous. A search of the biomarker and the simultaneous development of the companion diagnostic agent enter the mainstream of the development of new molecular target drug. Whereas the process of the drug development is complicated than before.