What factors offer price premium to sellers in online open marketplaces? It is important to study the relationships between trust in sellers and price premium because the research can give strategic guidelines to online open marketplaces by investigating the principle of electronic market and identifying the usefulness of trust indicators regarding sellers. Thus, the objective of our research is to identify the factors related to trust in sellers affecting price premium by investigating trust indicators of two typical domestic open marketplaces and analyzing data collected from real transactions. There are two types of models for online open marketplaces. One is the auction model and the other is the catalog based model. This study addresses the catalog model. This study proposes a research model representing the relationships between antecedents such as trust indicators on sellers, negative feedback, and assurance seals, and price premium. The research model also reflects the roles of price range in the relationships between independent variables such as trust indicators and negative feedback, and price premium as dependent variable. The research presents five hypotheses. First of all, we propose a trust function that calculates trust level in seller through trust indicators based on seller's feedback profile by applying AHP technique using questionnaire data collected from purchasers in online open marketplaces. To test five hypotheses, we used 241 transactions data of lower-priced, meddlepriced and higher-priced products from two typical open marketplaces such as Auction site and 11st site. The result of our empirical study indicates that negative feedback only has influence on price premium. The result is different from those of previous studies. The difference results from different pricing mechanisms and environmental change in domestic online open marketplaces. Herzberg's two-factor theory can explain the reason why four hypotheses were not supported. The negative feedback plays a role as motivator, whereas other factors such as trust indicators based on reputation systems and assurance seals given to sellers from open marketplace themselves play roles as hygiene factors. In other words, trust indicators and assurance seals are not motivators offering price premium through differentiation among sellers, but are only hygiene factors reducing transaction risks for purchasers in online open marketplaces. Thus,online open marketplaces need to develop new indicators representing trust in seller to help purchasers make their purchasing decision. Trust indicators including seller grade and selling satisfaction are not sufficient factors differentiating trustworthy sellers and untrustworthy sellers as if an emerging technology could not give a competitive advantage when it diffused to all competitive firms. Finally, sellers have to make efforts for reducing or eliminating negative feedback coming from purchaser's comments to get price premium.