Abstract:To treat environmental problems and to seek sustainable development, voluntary and cooperative efforts, which is really against the traditional mentality with the emphasis on the individual competitive optimization, became the key to maintain the sustainability of complex social and ecological systems. To understand the cooperative and voluntary individual's environmentally significant behavior (ESB), this paper focuses on the role of trust, and assesses the effect of trust on the relationship between existing factors and ESB. A structural equation model (SEM) is constructed to estimate the moderating effects of trust on ESB in Korea. We found that people with a negative view on strict environmental regulations do not exhibit ESB and thus nudge policies could be much more effective than the forceful measure. It is noteworthy that public private partnership, as a kind of optimal trust, should be more promoted in the environmental protection policies.