We study disturbance attenuation in output consensus networks consisting of passive linear time-invariant systems. When individual systems in a network are subject to exogenous disturbance, they may not be able to achieve output consensus perfectly. In such a case, it is important to design the network topology appropriately so that the individual systems reach consensus as closely as possible. In this paper, we provide a condition under which interconnections among the individual systems are advantageous in terms of disturbance attenuation assuming that the individual systems are passive and the interconnection topology is undirected.