A voice input device includes: a mastery level identifying device identifying a mastery level of a user with respect to voice input; and an input mode setting device switching a voice input mode between a guided input mode and an unguided input mode. In the guided input mode, preliminary registered contents of the voice input are presented to the user. The input mode setting device sets the voice input mode to the unguided input mode at a starting time when the voice input device starts to receive the voice input. The input mode setting device switches the voice input mode from the unguided input mode to the guided input mode at a switching time. The input mode setting device sets a time interval between the starting time and the switching time in proportion to the mastery level.