Plastic recycling system is designed by various stakeholders, such as consumers and recycling manufactures. The effect of plastic recycling depends on conditions on recycle technology, collection, transportation, and the intended products to be substituted by plastic recycling. Therefore, the relationship between the conditions and effects needs to be analyzed in order to design an appropriate recycling system. In this research, we analyzed the relationships between plastic recycling conditions and effects such as the consumption of fossil resources and CO(2) emission toward appropriate Japanese plastic recycling system. An analytic tool utilizing optimization technique was constructed to evaluate and generate plastic recycling scenarios. By this tool, the reduction effect of the consumption of naphtha, fuel oil, coal, and natural gas can be evaluated with the reduction of CO(2) emission through plastic recycling. The system can analyze the optimal distribution scenario of plastic wastes on such reduction effect of fossil resource consumption under specific weighting factors to each resource by linear programming. Based on this analysis, it was demonstrated that 286 sets of weighting factors generated independent 135 candidates. Defining a constraint on the reduction effects of CO(2) emission and naphtha consumption, effective candidates can be selected. If the constraint is that the reduction effects should be higher than 50% of their potentials, 28 scenarios are selected. The constructed system makes it possible to support the design of plastic recycling system from the viewpoints of reducing environmental load including fossil resource consumption.