A ring network system includes a plurality of node apparatuses that are sequentially connected through a transmission medium that is formed in a ring form. In the ring network system, the remaining node apparatuses, except for a first node apparatus of the plurality of node apparatuses pass an optical signal that is transmitted from the first node apparatus, and a second node apparatus corresponding to a destination of the optical signal among the remaining node apparatuses, extracts the optical signal while transferring the first optical signal to a next node apparatus of the second node apparatus.