In this paper, the impedance perceived by an operator of a robot in multilateral control system under constant communication time delay is considered. The multilateral control system is one of the methods which transmit tactile sense to many remote places. Time delay possibly makes the performance of the multilateral control system worse. For example, time delay makes an operator feels large operational force. The operational force means that the operator feels the force except the reaction force from the environment. Moreover, time delay makes the operator feels that the environment is softer than the real stiffness. In this paper, the multilateral control system with three robots is considered. By frequency characteristics of the impedance perceived by the operator, the effect of time delay on the impedance perceived by the operator is verified. The results obtained in the analysis are verified by experimental results.