A host providing system includes a physical host network switch which determines permission and non-permission of communication on the basis of whether or not information pieces indicating users correlated with information indicating a transmission source and information indicating a transmission destination included in communication data from a physical instance match each other, and controls the communication data on the basis of a determination result. Accordingly, since only communication between instances of the same user is permitted, and thus communication from a physical instance is appropriately controlled, it is possible to ensure security in the system.