Abstract
A collection system of classified garbage and rubbish structurally inherits a “social dilemma” that without contribution of most residences to the system classification efforts by contributors come to naught. The system effectively works only when majority contribute to the system. This study models the decision mechanism by residences on garbage classification and clarifies how they decide to cooperate to the system. Moreover, based on the model and the survey results effective policies for better classification of garbage are considered.