An elevator target floor registration unit, which displays an estimated amount of time until an assigned elevator car arrives, reduces feelings of uneasiness. Various target floor registration units by which a user may register a target floor are installed on respective floors of a building. The target floor registration units are connected to an elevator controller via an interface. The elevator controller: (a) assigns a most suitable elevator car corresponding to a user's target floor registered using the target floor registration unit; (b) computes an expected waiting time for the elevator assigned to arrive at the floor of the aforementioned registration; and (c) sends said pieces of information on the elevator assignment and the expected waiting time to aforementioned target floor registration unit in order to display them.