The global warming problem due to greenhouse gas emission has become very serious. Moreover, in the transportation section, the construction of a sustainable transportation system in the environment has been an important subject. Not only improvement of service level of modes, except those of private vehicles, but also consciousness for the environmental problem of an individual trip maker is important for eco-commuting promotion. Eco-consciousness can be changed under the influence of other people. The multi-agent simulation system for planning of ecocommuting promotion is developed using a social interaction model for eco-consciousness in this study. Modal shift is modeled by considering the result of a transport social experiment for eco-commuting promotion as reference. Influence of the promotion plan such as improvement of service level of public transport, promotion of individual eco-consciousness, and strengthening the interaction of individuals can be analyzed using the proposed model. Finally, it is concluded that the proposed multi-agent simulation with social interaction for eco-consciousness is useful for the planning of eco-commuting promotion.