To measure the effect of direct mail transmission.

A hall computer 100 sends direct mail to members of a group of selected member IDs to which the direct mail is sent, receives member IDs sent when members having received the direct mail load member cards in a terminal device 250 for member cards arranged in a game center, and computes the mail transmission effect according to the result of a decision on whether or not the member IDs are received within an event period, so the effect of the direct mail transmission can be measured.