抄録
Industry has a tendency to concentrate in a rather localized area. This phenomenon is now attracting the interest of many people and can be explained from two sides. From the negative side, the local concentrations of industries are now in a difficult situation, because of the competition mainly from Asian countries, and these industries are now targets of a revitalization policy. From the positive side, the concentrations offer a chance to create new high tech industries, upon which Japan is obliged to rely on in the future. This paper first analyses how a localized concentration begins and proceeds using a simple model of increasing returns. The model reveals that there is a threshold beyond which a concentration has an advantage over a non-concentrated area. The concentration proceeds until a certain amount of capacity has accumlated in the region. The saturation point differs much according to whether the concentration is derived by an internal economy or an external economy. In an internal economy, it is quite probable that a single big firm monopolies the industry. In an external economy, many small firms accumulate until extra profit rate is nullified. In a numerical example given in the paper, the internal economy case ceases to accumulate at about half the volume of the external economy case. In later sections, the concept “external economy” is examined. There is no such a case that can be called “external economy” in the sense that it only benefits small firms and not big firms. The external economy should be understood as a situation where economies of scale, as a function of total volume of productions, prevail and firms are prevented to grow beyond a certain size due to the existence of other reasons that increase the internal cost of the firm. In the last part of the paper, an advantage of the diversity is discussed and some policy implications are indicated.
