An electronic money system is provided which requires lower management and running cost, and features higher flexibility. An acquirer/brand holder managing an electronic money brand manages all keys used for authentication processing in the system, and issues the keys as necessary. The acquirer/brand holder distributes keys according to a tie-up agreement to IC card issuers, a POS center, an MMK center, and an affiliate merchant terminal unit. The POS center, the MMK center, and the affiliate merchant terminal unit are apparatuses for users to use the IC cards or for managing them. The acquirer/brand holder, however, does not distribute issued keys to cybershops which users can access by using a personal computer and a reader/writer. Instead, in this case the acquirer/brand holder saves the issued key itself, and carries out authentication processing with a predetermined IC card upon a request from the cybershop.