A resource allocation device includes a database of user and service information, a resource allocation management unit for determining whether a service request agrees with a service level agreement and whether it accepts a resource allocation request, a service level agreement unit for negotiating the service level agreement with the user, sending the received service request to the resource allocation management unit, acquiring the result of the resource allocation request, and transmitting the result of the resource allocation request to the user, a routing information management unit for obtaining a network configuring information, storing the network configuring information in the database, discovering the path to provide the service and storing the discovered path in the database to be reused and a policy control management unit for deciding a policy according to whether the service request and the resource allocation request are accepted.