This paper analyzes the structure of “overproduction” in light-breed horses in Japan. By analyzing both aspects of the breeding structure from the aspect of supply and the stable of situation from the aspect of demand, it is the intention of this paper to clarify the charac teristics “overproduction” in light-breed horses in the 1990's. As the 1st horse racing boom before and after 1970 brought on the 1st overproduction in the latter part of the 1970's, the 2nd horse racing boom in the latter part of the 1980's brought about the 2nd overproduction into the 1990's. However, “overproduction” in the 1990's fundamentally differed from that of the 1970's on the following points. First, the bubble economy in the latter part of the 1980's caused an abnormal expansion of purchasing power where the number of foals purchased greatly exceeded the demand. In other words, this brought about a breakdown of coordination in supply. As the bubble economy was of such an extensive scale, the rebound was likewise devastating in which the increase of the number bred was far greater than the previous “overproduction period.” Second, into the 1980's, as the foals and yearlings were dispersed and kept at the stud farms, the yearling training farms in the breeding area, the yearling training farms in and around the training centers, it gave the impression that a certain degree of the “overproduction” had been absorbed. But, the “overproduction” this time was so grave that even this absorbing function would no longer work. Third, the “overproduction” this time was an “overproduction” of only Thoroughbreds. There was a difference in scope with the previous overproduction in that there was an “over production” of both Thoroughbreds and Anglo-Arabs. This was because during this period, light-breed horse breeding continued to specialize on Thoroughbreds. At the present, there is no “overproduction” of Anglo-Arabs. However, depending on the subscription Anglo-Arab horse problem in National Racing and the degree of recession in Regional Public Racing, it isbelieved that eventually the recession in Anglo-Arabs will become a problem. At such a time, if Anglo-Arab horse management was forced to convert, even in a partial way, to Thoroughbred horse management, the “overproduction” of Thoroughbreds will probably become more serious. Fourth, during this period, the light-breed horse management as a principal occupation and specialization have further increased creating a Thoroughbred-inclined structure. For this reason, conversion to other forms of agriculture industry is difficult and countermeasures against “overproduction” become more difficult, both in management and regionally. For these reasons, demands may be forthcoming for drastic “countermeasures against overproduction.”