In this paper, the methodology for integrated assessment based on CBA (cost-benefit analysis) was proposed in consideration of stakeholders' preferences for multi-aspect impacts on the environment and civic life, and its applicability for public decision-making processes was discussed. The characteristics of this methodology are to integrate environmental, social and economic impacts into a single indicator in monetary value, and to reflect stakeholders' preferences to valuation of each impact category. Local impact categories are converted into monetary value using conjoint analysis and global impact categories are converted into monetary value with the coefficients estimated by EPS. In the case study of MSW (municipal solid waste) management system in Kawasaki City, three options focusing on separate collection and recycling of plastics waste were compared. The result of integrated assessment suggested that, in the case the social benefit derived from implementing separate collection itself was counted, the option where plastics waste was directly landfilled or recycled in blast furnaces was better than other options from the viewpoint of CBA. In the case the social benefit derived from implementing separate collection itself was not counted, the option where plastics waste was incinerated along with combustibles was judged to be better than others.