A hot-water supply system (1) remotely controls, via a server (50) and using a portable terminal device (30), a hot-water supply device (10) connectable to an external communication network (40). The hot-water supply system (1) is provided with a control unit which performs a notification process for notifying at least another, already-associated portable terminal device (30) that the portable terminal device (30) for performing remote control has been newly associated with the hot-water supply device (10). For example, a control unit of the server (50) performs the notification process as the control unit.