Environmental auditing, which constructs, evaluates and improves environmental management system, has attracted increasing attention in the world. Fundamentals of environmental auditing are the concepts of 'system' and 'environment' and the principle of entropy increase. In this study, environmental auditing was carried out at a festival in Hiroshima-Univ. in 1995. Measured were foods, vessels and fuel gas in incoming part, products by street stalls and garbage in outgoing part. Eatable and uneatable parts of the product were separated and measured. Garbage was measured by weight, and categorized according to material, type and source. It was found that unrecycled garbage was for approximately 39% (about 1.6t) of all garbage (about 4.0t). Unrecycled garbage from Street Stalls was approximately 400f all unrecycled garbage and that from consumer was 41%.0 While waste from factory at production part have been mainly focused, recently Green Consumerism appeared so as to focus on products (goods) at consumption part. Advantage and disadvantage were simulated on assumption that one-way vessels were converted to re-use vessels at a festival in Hiroshima-Univ. in 1995. Since by the conversion, emission of CO_2,garbage and material resource were reduced 3okg, 228kg and 126kg, respectively, the conversion plan have a merit overall. Additionally, it is also economically acceptable. This study made Co-op decide maximal support to improve the plan that is from one-way to re-use vessels at a festival in Hiroshima-Univ. in 1996. Environmental auditing will be carried out at a festival by converting one-way vessels to re-use vessels, and quantity of garbage and emission of CO_2 will be determined and elucidated.