This paper proposes systems' approaches for service science. There are several new approaches for service science. Vargo proposed Service Dominant Logic (SDL), which determines service value according to “value in use”. Kameoka and Oda defined service as supporting activities. Based on such new trends, we developed the concept of service system to maximize service value for customers. The service system requires 3 types of technologies, which are human analysis technologies, service optimization technologies and technologies for service value co-creation. The service science is very important for business in the 21^st century.