Provided a framework that allows a user who represents a group and carries out an accommodation reservation procedure to solicit participating members while holding an accommodation. The procedures includes: (1) receiving a tentative reservation application from an organizer, requesting approval from members, receiving responses to the request for approval from the members, and sequentially identifying a tentative reservation number, member and answer; (2) when the identified answer is “approved” (Yes in S1122), adding 1 to “number of members decided to participate” (S1124); (3) when the number of members decided to participate is the multiple of the maximum number of guests (Yes in S2026), adding 1 to “reservation placement plan quantity” (S2028), assigning a new reservation number, and registering reservation information of an order quantity 1 into the reservation DB (14) (S2030).