Focusing on the diversity of how people communicate with each other, the objective of the invention is to provide a signal-responsive device that achieves a digital-based method of communicating that has been nonexistent until now. Provided is a signal response operation device which sends, to a receiving device of a receiving subject, signals from a plurality of sending devices for which senders are not specified, and causes the receiving device to operate. A server registers the receiving device of the receiving subject, and groups and registers each sending device of a plurality of the senders which includes persons who have been selected by or have agreed with the receiving subject. By any of the plurality of senders operating the sending devices, the server sends a signal to the receiving device in response to the sending of a signal from the registered sender.