A destination floor registration device of an elevator comprising: a destination floor registration signal input unit that inputs a destination floor registration signal from a destination floor registration button placed in an elevator car; a boarding detection unit that detects that a passenger has boarded the elevator car; a voice output unit that outputs a voice message to the elevator car; a voice input unit that inputs a voice message from the elevator car; and a voice destination floor registration unit that, when the destination floor registration signal input unit does not input the destination floor registration signal after a predetermined time limit has elapsed since the passenger was detected to board the elevator car by the boarding detection unit, outputs a destination floor pronouncing request voice message to the elevator car via the voice output unit for requesting the passenger to pronounce a destination floor, and, when a voice message responding to the voice destination floor pronouncing request voice message is input via the voice input unit, performs a voice recognition process on the voice message input and performs destination floor registration for the elevator car based on a result of the voice recognition process, characterized by: the boarding detection unit being further adapted to determine whether or not a passenger who has newly boarded the elevator car is alone in the elevator car; and the voice destination floor registration unit is further adapted to, when the boarding detection unit has determined that the passenger who has newly boarded the elevator car is alone in the elevator car, output the destination floor pronouncing request voice message to the elevator car via the voice output unit. a destination floor registration signal input unit that inputs a destination floor registration signal from a destination floor registration button placed in an elevator car; a boarding detection unit that detects that a passenger has boarded the elevator car; a voice output unit that outputs a voice message to the elevator car; a voice input unit that inputs a voice message from the elevator car; and a voice destination floor registration unit that, when the destination floor registration signal input unit does not input the destination floor registration signal after a predetermined time limit has elapsed since the passenger was detected to board the elevator car by the boarding detection unit, outputs a destination floor pronouncing request voice message to the elevator car via the voice output unit for requesting the passenger to pronounce a destination floor, and, when a voice message responding to the voice destination floor pronouncing request voice message is input via the voice input unit, performs a voice recognition process on the voice message input and performs destination floor registration for the elevator car based on a result of the voice recognition process, the boarding detection unit being further adapted to determine whether or not a passenger who has newly boarded the elevator car is alone in the elevator car; and the voice destination floor registration unit is further adapted to, when the boarding detection unit has determined that the passenger who has newly boarded the elevator car is alone in the elevator car, output the destination floor pronouncing request voice message to the elevator car via the voice output unit.