Abstract: An automated cash transaction system that provides enhanced convenience for both customers and financial institutions by utilizing a mobile telephone and a computer network. The automated cash transaction system includes: a server which is connected to the computer network, and which distributes a transaction processing program for allowing the mobile telephone to carry out processing at least for user authentication and communications with an automated cash transaction machine; the mobile telephone which receives the transaction processing program from the server via the computer network, stores the received transaction processing program, and carries out the processing for user authentication and communications with the automated cash transaction machine in accordance with the transaction processing program; and the automated cash transaction machine which carries out automated cash transaction processing based on data entered through communications with the mobile telephone.