A lean manufacturing is desirable for sustainability of manufacturing sector in both developed and developing countries. Toyota Production System (TPS) is known as an efficient production system, but this paper proposes that the TPS can be extended to make the entire business process in the manufacturing enterprise efficient and value-added. A key issue is the production leveling or the smoothing of production that plays an important role in the Just-In-Time system. This paper discusses efficiency of the entire business process including marketing research, product design, production system design, production control, procurement, sales, and service by a view of the production leveling and value chain. In addition, the author differentiates the TPS from the Japan Production System (JPS) and the Lean Production System (LPS).