a group of information processing terminals including at least one mobile terminal capable of connecting to a mobile communications network;

a commerce server connected to an information and communications network; and

an agent connected to both the mobile communications network and the information and communications network, conducting electronic commerce for the mobile terminal so that a user of the mobile terminal purchases an article from the commerce server;

wherein: each of the information processing terminals includes:

an authorizing part for providing authorization for the agent to conduct electronic commerce for the information processing terminal; and

an authorization information notifying part for notifying the agent of information on the authorization;

the commerce server includes a procedure information notifying part for notifying the agent of information as to procedures for the electronic commerce; and

the agent, at which the line of the mobile terminal terminates, includes:

a first storage for storing the electronic commerce procedure information received from the commerce server;

a second storage for storing the authorization information received from the information processing terminal; and

an electronic commerce conducting part for, in response to a request from the information processing terminal, carrying out the procedures for the electronic commerce which the agent has the authorization to conduct according to the authorization information received from the information processing terminal based on the electronic commerce procedure information

wherein: each information processing terminal further includes:

a user authentication information obtaining part for obtaining user authentication information to identify its user;

a user authentication information notifying part for notifying the agent of the user authentication information; and

an authenticating part for authenticating the agent that is to conduct the electronic commerce on behalf of the information processing terminal using a digital signature contained in a digital certificate obtained from the agent;

the agent further includes an identifying part for determining whether the user of the information processing terminal is the party concerned with the electronic commerce based on the user authentication information received from the information processing terminal;

wherein the information processing terminal is configured to determine whether the agent is authorized to conduct the electronic commerce for the information processing terminal; and

wherein the agent is configured to determine whether the user of the information processing terminal is the party concerned with the electronic commerce so as to conduct the electronic commerce for the information processing terminal used by the party concerned with the electronic commerce.