In accordance with foreign opening system such as WTO/DDA, FTA, fishery products will lose its price competitiveness due to the rush of low priced fishery products from abroad. In calculating those damages, we have made an estimation of same products during the past. However, it can cause damages to the other fishery substitutes in the long term, and create spill-over effects to overall fishery products inducing substitution effects with imports. Currently, multidimensional studies on those effects are not being carried out. Throughout this study, I tried to find those substitute relationship caused by secondary or thirdly effects and show those degree as a cross-elasticity coefficient. For those purpose, I selected 14 representative fishery products and derived substitute relationship and then analysed price elasticity of substitutions based on demand function model. The result shows substitute relationship not only between fishery products but also with stock farm products to some degree. Consequently, it is important to consider effect on overall fishery products including alternative effects of fishery products in establishing the countermeasure for the forthcoming WTO/DDA and FTA negotiation. Also, it is required to consider every possible effects on the fishery products caused by alternative effects in compensating for the fishery damages which makes it possible to provide substantial help to fishermen.