It is generally accepted that using the same grading standard for agricultural products from the places of shipment to the consumers is hard to be realized. The grading standard which adopted by producers is not understood by consumers. General consumers have usually doubted and distrusted the present grading method. On the other hand, producers spent considerable time and labor on grading and sorting method of the mandarin oranges. Viewing the importance of grading standard for agricultural products, this study intended to reassess the grading method that currently used in the marketing process by basing on the data analysis. It is expected that the result of this study will lead to the clarification of the grading standard used by the people concerned and simplify it. The empirical study was carried out by using the data of tracing survey of the mandarin orange in which the technique of quantification theory to be tried. The following approaches were considered for grading system: (1) Deviation of the assessment values of grading standard (classified by quality and size) among different wholesale markets, (2) The transitional change of grading assessment at the different points of the marketing channel, (3) Method of simplification of the grading system. 1. The assessment values of "grade" (categorized by quality) and "class" (categorized by size) were often different at different markets even for the same product. The price quoted by Fukuoka market was higher for the "excellent" quality than other markets. The price difference arisen from market assessment was likely to be wider for the grade than the class. 2. How to retain the grading standard which was classified by producer was considered. The grading, though to be done by producers, was performed in such a way that suited the interests and convenience of middlemen, and it was altered at the retail level so that the early grading was not carried to the consumers. As a result the high quality of orange from the famous producing area and the ordinary quality from the other areas became indiscriminately at the retailer's shop. It was a common practice that only the name of famous producing area was retained but that of other areas were dropped out. This fact brought about the feeling of distrust from consumers against pricing. Then, there was no difference for the rate of market margin of orange of different quality for the middlemen, there was no difference in profit rate for high quality orange among different retailers but for the low quality one it had a great variation in profit rate. 3. The method of simplification of the grading sys t e m was considered. As mentioned above that grading was done to suit the interests and convenience of middlemen. Therefore, the analysis should be focused on market performance of these middlemen to simplify the grading. It should have two grades that were the "excellent" quality grade and the other, and had 3 sizes, namely, large (those of size 2 L and above), middle (size L, M), and small (size S and below) for assessing the present grading of the middlemen.