An alarm device for a vehicle includes state information obtaining unit, alarm information obtaining unit, alarming unit, and controlling unit. The state information obtaining obtains as state information at least one of information of an occupant, information of the vehicle, and information of a surrounding of the vehicle. The alarm information obtaining unit obtains alarm information. The alarming unit informs the occupant of the alarm information. The controlling unit determines an expiration time of the alarm information based on the state information obtained by the state information obtaining unit when the controlling unit receives the alarm information from the alarm information obtaining unit, wherein the control unit causes the alarming unit to inform the occupant of the alarm information while the expiration time is valid.