原料用馬鈴しょの取引様式と駆引行動

Abstract

There are mainly three ways of using potatoes, that is, 1) eating, 2) making starch, and 3) making chips. Potatoes for eating are transacted through a wholesale competitive "spot market" by auction. But potatoes for starch are transacted from farms to agricultual cooperative starch process factory directly, which means "internal transaction". Potatoes for chips are sold from farms to chips makers under the continuing contract, which means "customer market", I explain why such differences of transaction form occur by the concept "opportunism" in the case study of Tokachi Area, Hokkaido. Opportunism is defined as strategic behavior to realize individual advantage, involving self-interest seeking with guile. If either of saler or buyer transacts opportunisticly, distorted equilibrium point, which is advantageous to either, will be realized on the contract curve. Before the forms of internal transaction and customer market; continuing transaction forms are spread, Potatoes for starch and chips were transacted through imperfect spot market system. In this system either of saler or buyer was apt to transact opportunisticly. As for starch potatoes, the processors of starch abused the information impactedness opportunisticly, so the price of potatoes was reduced under the real price, which was advantageous to processors. Then farmer's cooperative began to operate process factory by themselves to exclude opportunism and actualize the real price. As to chips potatoes, when the demand of potatoes increased suddenly in 1970 concerned with EXPO '70, farmers broak their one-year contracts and raised the price too high opportunisticly. So there happened a lot of chips maker's bankruptcy. Then now, makers become making continuing contracts with farmers to keep the price constant. I conclude that, concerned with potatoes for starch and chips, continuing transaction forms are spread in stead of spot market to exclude opportunism.