PURPOSE: To sufficiently perform the perspiration action of a yam, to impart moisture absorbability and buffering action and to simplify packing work, in packing a large number of yams in a container, by interposing a buffer material composed of fine pieces of a water absorbable foamed resin between yams.

CONSTITUTION: Harvested and collected yams 1 having an appropriate size are mutually gathered and spread all over the bottom of a container made of corrugated cardboard or foamed polystyrene or a box 3 made of other appropriate material quality to be stacked over several layers. In this case, a proper carpet may be placed on the bottom of the box 3 for the purpose of buffering. A buffer material composed of saddle-shaped fine pieces prepared from a water absorbable foam resin is spread and interposed between the yams. In order to control humidity, water is preliminarily scattered to the fine pieces from a spray to impart proper humidity thereto. The yams are again stacked thereon. Since the moisture generated by the perspiration action of a yam is absorbed by the fine pieces made of the water absorbable foamed resin, a yam is not moistened or discolored and can withstand long-term preservation.