In a vehicle user-assistance system, a user's voice is acquired before the user enters a vehicle, and the mental state of the user is inferred based on the acquired voice. Then, it is determined whether the inferred mental state is an irritated state compared with a criterial value. When the mental state is an irritated state, navigation that relieves irritation is proposed to the user having entered the vehicle. Thus, the user starts to travel with his or her irritation reduced or relieved.