A locking and unlocking control system, comprising: a first information acquisition part configured to acquire presence information as to whether a first parcel to be collected by or being delivered by a first user is present in a predetermined region, the predetermined region being defined in a vehicle or a facility, the predetermined region having a door configured to be locked and unlocked through a locking and unlocking process, and the locking and unlocking process being performed by a locking and unlocking control device; and a locking and unlocking control part configured to execute a predetermined process so as not to permit unlocking of the door by a second user different from the first user, said second user delivering a second parcel to the predetermined region, when an access prohibition condition including both of following conditions are satisfied: (i) the locking and unlocking control part determines, based on the presence information, that the first parcel is present in the predetermined region, and (ii) the door is locked, wherein the locking and unlocking control system is configured to control, by issuing predetermined authentication information for causing the locking and unlocking control device to execute the locking and unlocking process, to a user terminal of each of the users at least including the second user, access of users including at least the second user to the predetermined region, wherein the locking and unlocking control system further comprises a second information acquisition part configured to acquire information on an access permission condition, associated with the first parcel, for permitting access to the predetermined region by the second user even when the first parcel is present in the predetermined region, wherein the locking and unlocking control part is configured: to permit the second user to unlock the door to deliver the second parcel to the predetermined region by not executing the predetermined process when the first parcel satisfies the access permission condition, even when the access prohibition condition is satisfied; and not to permit the second user to unlock the door by executing the predetermined process when the first parcel does not satisfy the access permission condition, when the access prohibition condition is satisfied, and wherein the second information acquisition part is configured to acquire the access permission condition set by the first user for the first parcel. a first information acquisition part configured to acquire presence information as to whether a first parcel to be collected by or being delivered by a first user is present in a predetermined region, the predetermined region being defined in a vehicle or a facility, the predetermined region having a door configured to be locked and unlocked through a locking and unlocking process, and the locking and unlocking process being performed by a locking and unlocking control device; and a locking and unlocking control part configured to execute a predetermined process so as not to permit unlocking of the door by a second user different from the first user, said second user delivering a second parcel to the predetermined region, when an access prohibition condition including both of following conditions are satisfied: (i) the locking and unlocking control part determines, based on the presence information, that the first parcel is present in the predetermined region, and (ii) the door is locked, wherein the locking and unlocking control system is configured to control, by issuing predetermined authentication information for causing the locking and unlocking control device to execute the locking and unlocking process, to a user terminal of each of the users at least including the second user, access of users including at least the second user to the predetermined region, wherein the locking and unlocking control system further comprises a second information acquisition part configured to acquire information on an access permission condition, associated with the first parcel, for permitting access to the predetermined region by the second user even when the first parcel is present in the predetermined region, wherein the locking and unlocking control part is configured: to permit the second user to unlock the door to deliver the second parcel to the predetermined region by not executing the predetermined process when the first parcel satisfies the access permission condition, even when the access prohibition condition is satisfied; and not to permit the second user to unlock the door by executing the predetermined process when the first parcel does not satisfy the access permission condition, when the access prohibition condition is satisfied, and to permit the second user to unlock the door to deliver the second parcel to the predetermined region by not executing the predetermined process when the first parcel satisfies the access permission condition, even when the access prohibition condition is satisfied; and not to permit the second user to unlock the door by executing the predetermined process when the first parcel does not satisfy the access permission condition, when the access prohibition condition is satisfied, and wherein the second information acquisition part is configured to acquire the access permission condition set by the first user for the first parcel.