隨著網際網路的普及率日益升高，許多消費者也逐渐轉向電子商務平台購物，而合購也成為了一種新興的網路購物方式。本研究從社群與資訊豐富度角度，以交易成本為中介，包含搜尋成本、監督成本及執行成本，探討影響消費者線上再合購意願的因素，在資訊豐富度方面包含產品資訊與推薦資訊，社群方面包含需求外部性與互惠，此外亦探討個人因素，包含從眾與價格意識，對於交易成本與再合購意願之間的干擾效果。本研究結果顯示需求外部性、互惠及資訊豐富度對於三種交易成本均有顯著的負向影響，而三種交易成本皆顯著負向影響消費者線上再合購意願。在個人因素干擾方面，從眾對於搜尋及執行成本與再合購意願的負向關係有顯著干擾效果，當消費者個人的從眾意識較強時，會減弱兩種交易成本與再合購意願的負向關係；而價格意識僅對於監督成本與再合購意願的負向關係有顯著干擾效果，當消費者個人的價格意識較強時，會增強監督成本與再合購意願的負向關係。

Nowadays, business models have been changed by the prevalence of Internet. Online group-buying has emerged as the advent of electronic commerce. By using online group-buying as the research context, this study investigates the influences of online community and information richness on transaction cost. Online community includes externality and mutual benefits, while information richness is composed of richness of product information, and richness of recommendation information. Transaction cost is regarded as mediator to have impacts on continuance intention. This study further explores the moderating effects of conformity and price consciousness on the relationship between transaction cost and continuance intention. The results show that externality, mutual benefits, and information richness have influences on transaction cost, including searching cost, implementing cost, and monitoring cost. Three kinds of transaction cost then have negative effects on continuance intention. With regards to personal characteristics, conformity moderatesthe relationship between searching cost and continuance intention, and the relationship between implementing cost and continuance intention. Price consciousness only moderates the relationship between monitoring cost and continuance intention.