This thesis examines the case of the Shimizu Port Lumber Industries Cooperative (SLC). This study looks at SLC's (1) background, (2) financing, and (3) activities of purchasing materials and merchandising, since 1952 (when the union was established) through to 1974 (when business declined after the first oil shock). The study relied on the analysis of historical documents held by SLC and a hearing survey.

The management executives of the organizations in Shimizu before and during wartime established SLC in 1952. SLC comprised many small-sized firms with commonalities such as facilities and products.

Small-sized firms found great benefits in strengthening their nexus with SLC and as such, increased their financial contributions toward the cooperative, significantly improving its capital adequacy ratio.

Two noteworthy things occurred: First, SLC - members visited North America multiple times to inspect the forests and sawmills. Second, Tenryu Seizai Co., Ltd., one of the executive firms of the SLC, shared its sales channel with members.

SLC played an important role in the import of lumber from North America to Japan. This provided a platform for small-sized firms to conduct business at the start of Japan's high economic growth period.

However, at the end of Japan's period of high economic growth, the need for a cooperative for small-sized firms decreased due to their improved marketing capabilities. Further, the sustainability of cooperation was limited under the leadership of management executives.