1. A transmission system having: a plurality of delivery server side routers which communicate with a plurality of delivery servers for delivering a content; and a client side router which communicates with a client device for receiving the content, the transmission system comprising: a database that stores server load states of the plurality of delivery servers, and respective individual link load states for a plurality of delivery paths defined between the plurality of delivery server side routers and the client side router; and a path control unit that determines a minimum load state delivery path having a minimum load state among the plurality of delivery paths, based on sums of the server load states and the respective individual link load states stored in the database, the path control unit using a virtual node connected to the plurality of delivery server side routers via virtual links, wherein the path control unit replaces the server load states of the plurality of delivery servers with individual link load states in directions from the virtual node via the virtual links, respectively, to the client side router, and determines a set of a delivery server and a delivery path by using the individual link load states.