This study conducted an empirical analysis considering the roles of negotiators to examine the effects of individual characteristics of negotiators on negotiation outcomes. The study used three variables—collectivism, power distance, and rationalism—as individual characteristics of negotiators, and for the empirical analysis, 196 subjects participated in single-issue bilateral face-to-face negotiations. The negotiation experiment was conducted by randomly pairing participants into 98 dyads, with each pair negotiating one-on-one for one hour. Participants performed the role of either buyer or supplier and received only information relevant to their assigned role. The study used 93 dyads for hypothesis testing, excluding 5 dyads that were difficult to analyze. The results revealed that in buyer-supplier bilateral negotiations, negotiators' individual characteristics had significant effects on negotiation outcomes, and these effects varied depending on the negotiator's role. Supplier collectivism had a significantly positive effect on supplier negotiation outcomes, whereas buyer collectivism had a significantly negative effect on buyer negotiation outcomes. Supplier and buyer authoritarianism did not have significant effects on their respective negotiation outcomes; however, supplier authoritarianism had a negative effect on supplier negotiation outcomes, while buyer authoritarianism conversely had a positive effect on buyer negotiation outcomes. Both supplier and buyer rationalism were found to have significantly negative effects on their own respective negotiation outcomes. The theoretical and practical implications of this study were discussed.