A data delivery method for delivering data that are object of delivery, these data containing observation time and observation results of a prescribed object of observation, to a data-using terminal includes steps of: executing a delivery process when a delivery condition has been met; storing delivery history information that indicates the delivery history of the delivery object data; and, based on the delivery history information, generating packaged delivery information, which is information in which a plurality of delivery destinations to which the same delivery object data are simultaneously delivered are placed in correspondence. In the delivery process, based on the packaged delivery information, all types of delivery object data that have been placed in correspondence with the delivery condition that has been met are delivered to the data-using terminals of all delivery destinations that have been placed in correspondence with the delivery condition.