Recently, Third Parties which are neither consumers nor suppliers have come to have a key role of constructing long-term brand. However, few marketing studies focus on importance of Third Parties, despite the many newspaper articles and economics papers on the subject. Most relevant studies discuss the suppliersʼ one-way brand creation or co-creation between consumers and suppliers.Among the studies conducted since the 2000s, a few focuses on the role of stakeholders around consumers in brand creation. But, there is few based on consumer behavior study. Otherwise, about the role of stakeholders around suppliers in brand creation, the arguments about current phenomenon (co-branding) which brands often add value of other brands is not enough, even though there are a few studies from the aspects of knowledge which connect with brand. And, studies of Third Parties have not been attracting attention until recently, although studies of reference group and Word of Mouth discussed influences of Third Parties to consumer behavior (especially purchase intention) in previous studies of consumer behavior in 80s. For the reasons stated above, I discussed the importance of research about Third Parties influence. In this study, I define Third Parties are people, companies and social environment that influence brand creation and brand consumption.