There have been proposed vehicle alarm devices that include vibrators installed in the seat surfaces of seats and give alarms to seated persons through vibrations of the vibrators (for example, see Patent Literature 1).  The vibrator of such a vehicle alarm device is installed between the cushion of the seat surface and a seat skin so as to be in contact with the seat skin.  By installing the vibrator between the cushion and the seat skin so as to be in contact with the seat skin, the vibrator contacts a seated person through the seat surface.  Thus, a vibration can be transmitted to the seated person more efficiently. 
Since an alarm is given to the seated person through the vibration of the vibrator, the seated person can be caused to feel the alarm through the vibration even if the seated person is driving the vehicle.