<p>A network design device includes: a division section for dividing a network having a plurality of channels and branch nodes into a plurality of linear partial networks using a predetermined terminating node or each branch node as the terminating nodes by allocating a device terminating one or more channels to be used to the terminating node and each branch node; an allocation section for allocating a linear relay device and/or a reproduction relay device to a node constituting each partial network according to the signal performance; a path formation section for forming a particular path by combining the partial networks to which a device has been allocated by the allocation means; and a deletion section for deleting a device terminating the channel allocated to the branch node for each path formed by the path formation section according to the signal performance.</p>
