Abstract: A system and method for mediating transactions among a plurality of social commerce businesses, which enable social commerce businesses to provide one large social commerce community and mediate transactions among the businesses to thereby provide a sound social commerce market in which the businesses compensate for weak points and achieve win-win results and enable transactions with overseas as well as domestic social commerce businesses. An embodiment of the transaction mediation computer converts specifications related to transactions to the format required by or suitable for a relevant social commerce businesses and provides the format such that transactions may be performed regardless of the nationality of the social commerce businesses, and accesses an electronic customs procedure computer and computers of domestic and overseas delivery companies so as to control the customs procedure and domestic and overseas delivery process.